CHANGELOG.md

v1.17.1

This patch release fixes four bugs (two are fixed in one commit), contains two internal improvements, and adds two other minor changes.

Bug fixes

• If you were using the MaxBufferedBytes option and ever hit the max, odds are likely that you would experience a deadlock eventually. That has been fixed.

• If you ever produced a record with no topic field and without using DefaultProduceTopic, or if you produced a transactional record while not in a transaction, AND if the client was at the maximum buffered records, odds are you would eventually deadlock. This has been fixed.

• It was previously not possible to set lz4 compression levels.

• There was a data race on a boolean field if a produce request was being written at the same time a metadata update happened, and if the metadata update has an error on the topic or partition that is actively being written. Note that the race was unlikely and if you experienced it, you would have noticed an OutOfOrderSequenceNumber error. See this comment for more details.

Improvements

• Canceling the context you pass to Produce now propagates in two more areas: the initial InitProducerID request that occurs the first time you produce, and if the client is internally backing off due to a produce request failure. Note that there is no guarantee on which context is used for cancelation if you produce many records, and the client does not allow canceling if it is currently unsafe to do so. However, this does mean that if your cluster is somewhat down such that InitProducerID is failing on your new client, you can now actually cause the Produce to quit. See this comment for what it means for a record to be "safe" to fail.

• The client now ignores aborted records while consuming only if you have configured FetchIsolationLevel(ReadCommitted()). Previously, the client relied entirely on the FetchResponse AbortedTransactions field, but it's possible that brokers could send aborted transactions even when not using read committed. Specifically, this was a behavior difference in Redpanda, and the KIP that introduced transactions and all relevant documents do not mention what the broker behavior actually should be here. Redpanda itself was also changed to not send aborted transactions when using read committed, but we may as well improve franz-go as well.

• Decompression now better reuses buffers under the hood, reducing allocations.

• Brokers that return preferred replicas to fetch from now causes an info level log in the client.

Relevant commits

• 305d8dc kgo: allow record ctx cancelation to propagate a bit more
• 24fbb0f bugfix kgo: fix deadlock in Produce when using MaxBufferedBytes
• 1827add bugfix kgo sink: fix read/write race for recBatch.canFailFromLoadErrs
• d7ea2c3 bugfix fix setting lz4 compression levels (thanks @asg0451!)
• 5809dec optimise: use byteBuffer pool in decompression (thanks @kalbhor!)
• cda897d kgo: add log for preferred replicas
• e62b402 improvement kgo sink: do not back off on certain edge case
• 9e32bf9 kgo: ignore aborted txns if using READ_UNCOMMITTED

v1.17.0

This long-coming release, four months after v1.16.0, adds support for Kafka 3.7 and adds a few community added or requested APIs. There will be a kadm release shortly following this one, and maybe a plugin release.

This adds full support for KIP-951, as well as protocol support for KIP-919 (which has no client facing features) and KIP-848 (protocol only, not the feature!). KIP-951 should make the client faster at handling when the broker moves partition leadership to a different broker.

There are two fairly minor bug fixes in the kgo package in this release, both described below. There is also one bugfix in the pkg/sr independent (and currently) untagged module. Because pkg/sr is untagged, the bugfix was released a long time ago, but the relevant commit is still mentioned below.

Bug fixes

• Previously, upgrading a consumer group from non-cooperative to cooperative while the group was running did not work. This is now fixed (by @hamdanjaveed, thank you!).

• Previously, if a cooperative consumer group member rebalanced while fetching offsets for partitions, if those partitions were not lost in the rebalance, the member would call OnPartitionsAssigned with those partitions again. Now, those partitions are passed to OnPartitionsAssigned only once (the first time).

Improvements

• The client will now stop lingering if you hit max buffered records or bytes. Previously, if your linger was long enough, you could stall once you hit either of the Max options; that is no longer the case.

• If you are issuing admin APIs on the same client you are using for consuming or producing, you may see fewer metadata requests being issued.

There are a few other even more minor improvements in the commit list if you wish to go spelunking :).

Features

• The Offset type now has a new method AtCommitted(), which causes the consumer to not fetch any partitions that do not have a previous commit. This mirrors Kafka's auto.offset.reset=none option.

• KIP-951, linked above and the commit linked below, improves latency around partition leader transfers on brokers.

• Client.GetConsumeTopics allows you to query what topics the client is currently consuming. This may be useful if you are consuming via regex.

• Client.MarkCommitOffsets allows you to mark offsets to be committed in bulk, mirroring the non-mark API CommitOffsets.

Relevant commits

franz-go

• a7caf20 feature kgo.Offset: add AtCommitted()
• 55dc7a0 bugfix kgo: re-add fetch-canceled partitions AFTER the user callback
• db24bbf improvement kgo: avoid / wakeup lingering if we hit max bytes or max records
• 993544c improvement kgo: Optimistically cache mapped metadata when cluster metadata is periodically refreshed (thanks @pracucci!)
• 1ed02eb feature kgo: add support for KIP-951
• 2fbbda5 bugfix fix: clear lastAssigned when revoking eager consumer
• d9c1a41 pkg/kerr: add new errors
• 54d3032 pkg/kversion: add 3.7
• 892db71 pkg/sr bugfix sr SubjectVersions calls pathSubjectVersion
• ed26ed0 feature kgo: adds Client.GetConsumeTopics (thanks @UnaffiliatedCode!)
• 929d564 feature kgo: adds Client.MarkCommitOffsets (thanks @sudo-sturbia!)

kfake

kfake as well has a few improvements worth calling out:

• 18e2cc3 kfake: support committing to non-existing groups
• b05c3b9 kfake: support KIP-951, fix OffsetForLeaderEpoch
• 5d8aa1c kfake: fix handling ListOffsets with requested timestamp

v1.16.1

This patch release fixes one bug and un-deprecates SaramaHasher.

SaramaHasher, while not identical to Sarama's partitioner, actually is identical to some other partitioners in the Kafka client ecosystem. So, the old function is now un-deprecated, but the documentation correctly points you to SaramaCompatHasher and mentions why you may still want to use SaramaHasher.

For the bug: if you tried using CommitOffsetsSync during a group rebalance, and you canceled your context while the group was still rebalancing, then CommitOffsetsSync would enter a deadlock and never return. That has been fixed.

• cd65d77 and 99d6dfb kgo: fix bug
• d40ac19 kgo: un-deprecate SaramaHasher and add docs explaining why

v1.16.0

This release contains a few minor APIs and internal improvements and fixes two minor bugs.

One new API that is introduced also fixes a bug. API-wise, the SaramaHasher was actually not a 1:1 compatible hasher. The logic was identical, but there was a rounding error because Sarama uses int32 module arithmetic, whereas kgo used int (which is likely int64) which caused a different hash result. A new SaramaCompatHasher has been introduced and the old SaramaHasher has been deprecated.

The other bugfix is that OptValue on the kgo.Logger option panicked if you were not using a logger. That has been fixed.

The only other APIs that are introduced are in the kversions package; they are minor, see the commit list below.

If you issue a sharded request and any of the responses has a retryable error in the response, this is no-longer returned as a top-level shard error. The shard error is now nil, and you can properly inspect the response fully.

Lastly (besides other internal minor improvements not worth mentioning), metadata fetches can now inject fake fetches if the metadata response has topic or partition load errors. This is unconditionally true for non-retryable errors. If you use KeepRetryableFetchErrors, you can now also see when metadata fetching is showing unknown topic errors or other retryable errors.

• a2340eb improvement pkg/kgo: inject fake fetches on metadata load errors
• d07efd9 feature kversion: add VersionStrings, FromString, V3_6_0
• 8d30de0 bugfix pkg/kgo: fix OptValue with no logger set
• 012cd7c improvement kgo: do not return response ErrorCode's as shard errors
• 1dc3d40 bugfix: actually have correct sarama compatible hasher (thanks @C-Pro)

v1.15.4

This patch release fixes a difficult to encounter, but fatal-for-group-consuming bug.

The sequence of events to trigger this bug:

• OffsetCommit is issued before Heartbeat
• The coordinator for the group needs to be loaded (so, likely, a previous NOT_COORDINATOR error was received)
• OffsetCommit triggers the load
• a second OffsetCommit happens while the first is still running, canceling the first OffsetCommit's context

In this sequence of events, FindCoordinator will fail with context.Canceled and, importantly, also return that error to Heartbeat. In the guts of the client, a context.Canceled error should only happen when a group is being left, so this error is recognized as a group-is-leaving error and the group management goroutine exits. Thus, the group is never rejoined.

This likely requires a system to be overloaded to begin with, because FindCoordinator requests are usually very fast.

The fix is to use the client context when issuing FindCoordinator, rather than the parent request. The parent request can still quit, but FindCoordinator continues. No parent request can affect any other waiting request.

This patch also includes a dep bump for everything but klauspost/compress; klauspost/compress changed go.mod to require go1.19, while this repo still requires 1.18. v1.16 will change to require 1.19 and then this repo will bump klauspost/compress.

There were multiple additions to the yet-unversioned kfake package, so that an advanced "test" could be written to trigger the behavior for this patch and then ensure it is fixed. To see the test, please check the comment on PR 650.

• 7d050fc kgo: do not cancel FindCoordinator if the parent context cancels

v1.15.3

This patch release fixes one minor bug, reduces allocations on gzip and lz4 decompression, and contains a behavior improvement when OffsetOutOfRange is received while consuming.

For the bugfix: previously, if the client was using a fetch session (as is the default when consuming), and all partitions for a topic transfer to a different broker, the client would not properly unregister the topic from the prior broker's fetch session. This could result in more data being consumed and discarded than necessary (although, it's possible the broker just reset the fetch session anyway, I'm not entirely positive).

• fdf371c use bytes buffer instead of ReadAll (thanks @kalbhor!)
• e6ed69f consuming: reset to nearest if we receive OOOR while fetching
• 1b6a721 bugfix kgo source: use the proper topic-to-id map when forgetting topics

v1.15.2

This patch release fixes two bugs and changes Mark functions to be no-ops when not using AutoCommitMarks to avoid confusion. This also includes a minor commit further improving the sticky balancer. See the commits for more details.

• 72778cb behavior change kgo: no-op mark functions when not using AutoCommitMarks
• e209bb6 bugfix kgo: pin AddPartitionsToTxn to v3 when using one transaction
• 36b4437 sticky: further improvements
• af5bc1f bugfix kgo: be sure to use topics when other topics are paused

v1.15.1

This patch release contains a bunch of internal improvements to kgo and includes a bugfix for a very hard to encounter logic race. Each improvement is a bit focused on a specific use case, so I recommend reading any relevant-to-you commit message below.

As well, the kversion package now detects Kafka 3.6, and the kgo package now handles AddPartitionsToTxn v4 (however, you will probably not be issuing this request).

Lastly, this release is paired with a minor kadm release, which adds the ErrMessage field CreateTopicsResponse and DeleteTopicsResponse, and, importantly, fixes a data race in the ApiVersions request.

franz-go

• 2a3b6bd improvement kversion: detect 3.6
• fe5a660 improvement kgo: add sharding for AddPartitionsToTxn for KIP-890
• b2ccc2f improvement kgo: reintroduce random broker iteration
• 54a7418 improvement kgo: allow PreTxnCommitFnContext to modify empty offsets
• c013050 bugfix kgo: avoid rare panic
• 0ecb52b improvement kgo: do not rotate the consumer session when pausing topics/partitions
• 1429d47 improvement sticky balancer: try for better topic distribution among members

kadm

• 1955938 bugfix kadm: do not reuse ApiVersions in many concurrent requests
• 66974e8 feature kadm: include ErrMessage in topic response

v1.15.0

This release comes 74 days (just over two months) since the last minor release. This mostly contains new features, with one relatively minor but important bug addressed (and one very minor bug fixed).

Bug fixes

• Fetch sessions now properly send forgotten topics if we forget the entire topic (not just individual partitions while other partitions are still consumed on the broker). For long-running clients where partitions move around the cluster a bunch over time, this ensures we are not sending requests with null topics / null topic IDs. See #535 for more details.
• If the client talks to an http endpoint, we now properly detect the bytes 'HTTP' and send a more relevant error message. This previously existed, but used the wrong int32 internally so 'HTTP' was not properly detected (thanks @alistairking!).

Features

• RecordReader now supports %v{json} to parse json inputs
• RecordReader now supports %v{}, an empty no-op formatting directive
• Adds PurgeTopicsFromProducing and PurgeTopicsFromConsuming to purge either the producing or consuming half of the client, if you are producing to and consuming from the same topics in the same client.
• The new ConsiderMissingTopicDeletedAfter option allows finer grained control for how long a regexp-discovered topic can be missing on the cluster before the topic is considered deleted (and then internally purged in the client)
• Adds NewErrFetch to create a single-error Fetches, for use in end-user tests / stubs.
• The new MaxBufferedBytes option can control how many bytes are buffered when producing, an option similar to MaxBufferedRecords.
• Adds BufferedFetchBytes and BufferedProduceBytes to return the total bytes in records buffered (note this counts only keys, values, and headers).
• Adds PreTxnCommitFnContext to allow custom Metadata annotation for transactional commits.
• Adds LeaveGroupContext to control how long leaving a group can take, as well as to return any leave group error.

Relevant commits

franz-go

• 4dcfb06 feature kgo: add LeaveGroupContext
• 910e91d and 60b601a feature kgo: add PreTxnCommitFnContext
• c80d6f4 feature kgo: add Buffered{Fetch,Produce}Bytes
• 304559f feature kgo: support MaxBufferedBytes
• 310a5da feature kgo: add NewErrFetch
• 504a9d7 feature kgo: expose ConsiderMissingTopicDeletedAfter
• 253e1a9 feature kgo: add PurgeTopicsFrom{Producing,Consuming}
• 055e2d8 improvement kgo record formatter: accept %v{} to be a no-op (plain read/format)
• 37edfb9 improvement kgo.RecordReader: support %v{json} to read json values
• 8a9a459 bugfix kgo: track topic IDs in the fetch session
• 9d25d3a bugfix kgo: fix typo in parseReadSize to properly detect and warn about talking to HTTP endpoints (thanks @alistairking!)

kadm

This release comes with a corresponding kadm release that contains a few behavior changes and improvements.

• bfd07b2 kadm: fix occasionally empty topic/partitions in Lag
• 00ac608 kadm: change FetchOffsetsForTopics to only return requested topics by default

v1.14.4

This small patch fixes kversion.VersionGuess to properly guess versions against zookeeper broker versions v2.7 through 3.4. See the commit for details.

• 5978156 bugfix kversion: fix version detection for Kafka v2.7 through 3.4

v1.14.3

This patch fixes regex consuming a deleted topic causing an unending internal loop of metadata reloading (trying to discover where the topic went).

• 627d39a bugfix kgo: fix / improve handling deleted topics while regex consuming

v1.14.2

This patch fixes an internal logic race that can be easily encountered when specifying exact offsets to consume from. If you encountered this bug, your consumer could just stop consuming for an indeterminite amount of time. This bug has existed for a long time and relies on both the client being slow and the broker being fast to hit.

• 1f696ca bugfix kgo: avoid a consumer logic race where the consumer stops consuming

v1.14.1

This patch release, quick on the heels of v1.14.0, fixes a race condition introduced in v1.14 in the PauseFetchTopics and PauseFetchPartitions functions, a second race condition that can occur when purging a topic, and fully addresses [#493][twmb#493] which was not completely addressed in v1.14.0.

• 8c785fa bugfix kgo: fix race between client closing and purging
• dc5283e kgo: re-fix #493, supporting other buggy clients, and add a test
• 32ac27f bugfix kgo: ensure assignPartitions is locked when pausing topics/partitions

v1.14.0

This release contains a few new APIs, one behavior change, and one minor bugfix.

Bug fixes

Previously, HookBrokerRead and HookBrokerE2E could not be used at the same time. This has been fixed.

Behavior changes

PauseFetch{Topics,Partitions} now causes the client to drop all buffered fetches and kill all in-flight fetch requests. Importantly, this also means that once you pause, it is no longer possible for what you paused to be returned while polling. Previously, the client made no attempt to clear internal buffers / in flight requests, meaning you could receive paused data for a while.

Seed brokers now show up in logs as seed_### rather than seed ### (an underscore has been added).

Features

• kgo.Offset now has an EpochOffset getter function that allows access to the actual epoch and offset that are inside the opaque Offset type.
• AddConsumePartitions allows adding individual partitions to consume, and the new counterpart RemoveConsumePartitions allows removing individual partitions from being consumed. Removing is different from purging, please see the docs.
• KeepRetryableFetchErrors bubbles up retryable errors to the end user that are encountered while fetching. By default, these errors are stripped.
• kversion now supports Kafka 3.5
• kversion now supports version guessing against KRaft by default
• kgo.DialTLS now exists to even more easily opt into TLS.
• kgo.Client.Opts now exists to return the original options that were used to configure the client, making initializing new clients easier.
• kgo.NodeName returns a string form of a broker node name. Internally, seed brokers use math.MinInt32 for node IDs, which shows up as massively negative numbers in logs sometimes. NodeName can help convert that to seed_<#>.

Relevant commits

• c3b083b improvement kgo: do not returned paused topics/partitions after pausing
• e224e90 bugfix kgo: allow HookBrokerRead and HookBrokerE2E to both be called
• 875761a feature kgo Offset: add EpochOffset getter field
• c5d0fc5 kgo: add a debug log for stripping retryable errors from fetches
• b45d663 kgo: add more context to opportunistic metadata loads while fetching
• 9dae366 kgo: allow retries on dial timeouts
• 00e4e76 kgo: tolerate buggy v1 group member metadata
• 34c8b3d feature kgo: add AddConsumePartitions and RemoveConsumePartitions
• b5cafba sasl: validate non-empty user/pass/token
• 76d2e71 feature kgo: add KeepRetryableFetchErrors
• 0df3ec0 kgo: fix new niche CI problem against Kafka 3.5
• 8ff1d0d feature pkg/kversion: attempt to guess KRaft by default as well
• e92f5d9 feature pkg/kversion: detect v3.5
• f1b923e feature kgo: add DialTLS option
• 9667967 feature kgo.Client: add Opts to return the original opts, to allow seeding new clients
• 8e14928 feature kgo: add NodeName for easy user formatting of internal seed node IDs

v1.13.6

This minor patch release allows an injected fake fetch to be returned if that is the only fetch ready to be returned. A fake fetch is a fetch that actually does not contain any data, but instead contains an error (and may contain an empty topic with a single 0 partition). Previously, a fake fetch could only be returned if actual data was also ready to be returned. Now, a fake fetch can always be returned. Fake fetches are most commonly experienced if you are unable to join a group -- the client injects a fake fetch to notify you, the client, that an error occurred. This patch actually allows you to consume that error.

• 5c87ce0 consumer: return from Poll if the only error is an injected fake

v1.13.5

This tiny patch release relaxes SASL/PLAIN to ignore any server response. This patch is only useful if you are using this client against Tencent (at least as we known at this moment). A normal broker does not reply to a successful PLAIN auth with any data, but Tencent apparently does. Sarama and the Kafka client itself both seem to ignore extra data once auth is successful, and if a broker actually rejected the auth then the broker would close the connection, so ignoring this data seems fine.

• 3addecc sasl plain: ignore any challenge data

v1.13.4

This bugfix release fixes a race condition when calling client.Close. This bug was introduced in commit e45cd72 in release v1.13.0. If a metadata request discovers a new broker as the client is closing, there is a tiny window where the metadata goroutine can update a map that the Close function is also concurrently accessing. The commit in this release fixes that by guarding the Close access with a mutex.

• ee3d7c1 bugfix kgo: fix race condition in close (thanks @matino

v1.13.3

This minor patch release adds a few internal improvements and fixes no bugs.

Release 1.13.2 patched commits from occuring between join and sync; this patch extends that to blocking LeaveGroup or Close if an active join and sync is occurring. This is necessary because revoke callbacks are called while leaving a group, and usually, you commit in a revoke callback.

A few extra logs are added, some areas of code are better, and a context.Canceled error that could occasionally be returned in fetches when an internal consumer session changed is no longer returned.

This release went through three+ straight days of looped integration testing on two laptops to track down extremely rare test failures; those have been tracked down.

Lastly, if you use a regex consumer and delete topics, the client now internally purges and stops fetching those topics. Previously, any topic discovered while regex consuming was permanently consumed until you manually called PurgeTopicsFromClient.

• bb66f24 kgo: purge missing-from-meta topics while regex consuming
• f72fdaf kgo: always retry on NotLeader for sharded requests
• 682d1f8 kgo: add info log when the client is throttled
• 88fa883 kgo: avoid counting pinReq version failures against retries
• de53fda kgo: add a bit more context to sharded logs, avoid info log on Close
• 7338bcf kgo: avoiding context.Canceled fetch from List/Epoch, improve testing&logs
• 055b349 consumer: do not use the partition epoch when assigning offsets
• d833f61 group consuming: block LeaveGroup between join&sync

v1.13.2

This patch improves the behavior of committing offsets while a rebalance is happening.

In Kafka, if a commit arrives on the broker between JoinGroup and SyncGroup, the commit is rejected with REBALANCE_IN_PROGRESS. If a commit is started before JoinGroup but arrives to the broker after SyncGroup, the commit is rejected with INVALID_GENERATION.

This patch changes how committing offsets interacts with join&sync: a client that is joining the group will block OffsetCommit (preventing the first error), and issuing an OffsetCommit will block the client from entering JoinGroup (preventing the second error).

Previously, you could occasionally encounter these errors with the cooperative-sticky group balancer because the standard behavior for eager balancers is to commit in OnPartitionsRevoked before all partitions are dropped at the end of a group session. You now should no longer encounter these errors during a commit at all with any balancer unless something is going quite wrong (massive client timeouts or broker hangs).

This does mean that OffsetCommit may take longer if you happen to commit in while a client is joining and the join&sync takes a long time.

• ee70930 kgo groups: block join&sync while a commit is inflight

v1.13.1

This patch release fixes a bug where a producer could enter a deadlock if a topic is deleted and recreated very quickly while producing.

• 769e02f producer: avoid deadlock when when quickly recreating a topic

v1.13.0

This release contains a few new APIs, two rare bug fixes, updates to plugins, and changes the library to now require 1.18.

Go version

This library has supported Go 1.15 since the beginning. There have been many useful features that this library has not been able to use because of continued backcompat for 1.15. There is really no reason to support such an old version of Go, and Go itself does not support releases prior to 1.18 -- and 1.18 is currently only supported for security backports. Switching to 1.18 allows this library to remove a few 1.15 / 1.16 backcompat files, and allows switching this library from interface{} to any.

Behavior changes

If group consuming fails with an error that looks non-retryable, the error is now injected into polling as a fake errored fetch. Multiple people have ran into problems where their group consumers were failing due to ACLs or due to network issues, and it is hard to detect these failures: you either have to pay close attention to logs, or you have to hook into HookGroupManageError. Now, the error is injected into polling.

Bug fixes

This release contains two bug fixes, one of which is very rare to encounter, and one of which is very easy to encounter but requires configuring the client in a way that (nearly) nobody does.

Rare: If you were using EndAndBeginTransaction, there was an internal race that could result in a deadlock.

Rare configuration: If you configured balancers manually, and you configured CooperativeSticky with any other eager balancer, then the client would internally sometimes think it was eager consuming, and sometimes think it was cooperative consuming. This would result in stuck partitions while consuming.

Features

• HookClientClosed: A new hook that allows a callback when the client is closed.
• HookProduceRecordPartitioned: A new hook that is called when a record's partition is chosen.
• Client.ConfigValue: Returns the value for any configuration option.
• Client.ConfigValues: Returns the values for any configuration option (for multiple value options, or for strings that are internally string pointers).
• kadm: a few minor API improvements.
• plugin/klogr: A new plugin that satisfies the go-logr/logr interfaces.
• pkg/kfake: A new experimental package that will be added to over time, this mocks brokers and can be used in unit testing (only basic producing & consuming supported so far).

Relevant commits

• 1b229ce kgo: bugfix transaction ending & beginning
• 461d2ef kgo: add HookClientClosed and HookProduceRecordPartitioned
• 3a7f35e kgo.Client: add UpdateFetchMaxBytes
• b0fa1a0 kgo.Client: add ConfigValue and ConfigValues
• b487a15 kgo: inject the group lost error into polling as *ErrGroupLost
• bc638b0 plugin/kotel.Tracer: add KeyFormatter, only accept utf8 keys
• a568b21 bugfix kgo: do not default to eager if there is any eager balancer
• bf20ac0 plugin/kzap: support LogLevelNone
• a9369be kadm: add state config altering using the older AlterConfigs request
• f5ddf71 kadm: add NumPartitions,ReplicationFactor,Configs to CreateTopicResponse
• e45cd72 consuming: close fetch sessions when closing the client
• d8230ca plugin/klogr: support for go-logr
• 0f42e43 check hooks and flatten slices of hooks

v1.12.1

This patch adds back the pre-v1.11.7 behavior of returning UNKNOWN_TOPIC_ID when consuming. Patch v1.11.7 explicitly stripped this error because it was found during testing that Kafka 3.4 now returns the error occasionally when immediately consuming from a new topic (i.e. in tests), and the error is explicitly marked as retryable within the Kafka source code. However, with topic IDs, there is no way for a client to recover if the topic has been deleted and recreated. By returning the error, end users can notified that their client is in a fatal state and they should restart. In the future, I will add an option to consume recreated topics.

• efe1cdb consumer: return UnknownTopicID even though it is retryable

v1.12.0

This release is tested against Kafka 3.4, and kversion can now properly version guess 3.4. There are two external kgo features in this release and there is one internal feature.

Externally,

• Client.CommitMarkedOffsets makes committing marked offsets a bit easier
• Client.UpdateSeedBrokers allows for updating seed brokers, which can be useful on extremely long lived clients.

Internally,

• KIP-792 improves fencing of zombie group consumers using cooperative rebalancing

• c5f86ea feature kgo.Client: add UpdateSeedBrokers(...string) error
• 3e45339 internal improvement group balancer: support KIP-792
• fe727f8 feature kversion: cut Kafka 3.4
• 6751589 feature pkg/kgo: add Client.CommitMarkedOffsets (thanks @celrenheit!)

v1.11.7

The integration test introduced in v1.11.6 was frequently failing in CI. After some investigation, the panic is caused from PurgeTopicsFromClient while a load of offsets was happening (i.e. consuming was being initialized). That race is specifically easily triggered in the integration test.

This patch also relaxes the error stripping while consuming. While consuming, retryable errors are stripped. The errors that were stripped was a small specific set that was originally taken from Sarama (nearly 4yr ago). Kafka 3.4 returns a new retryable error frequently if consuming against a topic immediately after the topic is created. This patch changes the error set to just strip all retryable errors, since the kerr package already indicates which errors are retryable. This is more compatible against the broker returning errors that are retryable.

This is the last commit in the v1.11 series -- immediately after tagging this, I will be working on v1.12 which will officially test against Kafka 3.4.

• 17567b0..78a12c3 bugfix consumer: fix potential panic when calling PurgeTopicsFromClient
• 17567b0 improvement kgo: always strip retryable errors when consuming

v1.11.6

v1.11.5 introduced a regression when:

• Using a direct consumer (not a consumer group)
• Using ConsumePartitions
• Not specifying all partitions in the topic

With the above setup, 1.11.5 introduced a bug that would consume all partitions in the topic, i.e. all partitions in a topic that were not specified in ConsumePartitions.

This patch restores the old behavior to only consume partitions that are requested. This patch also makes it possible to purge topics or partitions from the direct consumer, and makes it possible to re-add a topic. Lastly, three integration tests were added to ensure that the problems fixed in 1.11.5 and in this patch do not crop up again.

• edd0985 bugfix kgo: patch ConsumePartitions regression from 1.11.5

v1.11.5

v1.11.4 is retracted and because it actually requires a v2 release. When a breaking kmsg release must happen, v2 of franz-go will happen and I will make a change thorough enough such that major kmsg changes will not require a major franz-go change again.

When this repo was initially written, the Kafka documentation for the wire serialization of a Kafka record was wrong and different from how things were actually implemented in the Java source. I used the documentation for my own implementation. The documentation was later fixed.

What this means is that in this repo, kmsg.Record.TimestampDelta should be changed from an int32 to int64. Rather than release a major version of kmsg, I have added a TimestampDelta64 field.

The old 32 bit timestamp delta meant that this package could only represent records that had up to 24 days of a delta within a batch. Apparently, this may happen in compacted topics.

More minor: previously, AddConsumeTopics did not work on direct consumers nor on a client that consumed nothing to begin with. These shortcomings have been addressed.

• 12e3c11 bugfix franz-go: support 64 bit timestamp deltas
• f613fb8 bugfix pkg/kgo: patch AddConsumeTopics

v1.11.3

This patch release fixes a panic that can occur when fetching offsets in the following scenario:

• You are fetching offsets for a group that the client has not yet loaded internally
• The internal load's FindCoordinator request fails OR the group cannot be loaded

FindCoordinator usually does not fail outright because the request internally retries. As well, the group load is usually successful. Group loading only fails if you are unauthorized to describe the group or if the group coordinator is not loaded.

The most common case to encounter this error is when you issue a group request against a new cluster. The first time a group request is seen, the group coordinator loads. While loading, group requests are failed with COORDINATOR_LOAD_IN_PROGRESS or some other similar error.

• 5289ef6 bugfix kgo.Client: avoid panic in OffsetFetchRequest when coordinator is not loaded

v1.11.2

This patch release fixes HookFetchRecordUnbuffered never being called if a hook also implemented HookFetchRecordBuffered. No existing plugin currently implements these hooks (though one will soon), so this patch is only relevant to you if you manually have added these hooks.

• 2a37df9 bugfix kgo: patch HookFetchRecordUnbuffered

v1.11.1

This patch release fixes a bug in ConsumePreferringLagFn. The code could panic if you:

• Consumed from two+ topics
• Two of the topics have a different amount of partitions
• The single-partition topic has some lag, the topic with more partitions has one partition with no lag, and another partition with more lag than the single-partition topic

In this case, the code previously would create a non-existent partition to consume from for the single-partition topic and this would immediately result in a panic when the fetch request was built.

See the commit for more details.

• 38f2ec6 bugfix pkg/kgo: bugfix ConsumePreferringLagFn

v1.11.0

This is a small release containing two minor features and a few behavior improvements. The MarkedOffsets function allows for manually committing marked offsets if you override OnPartitionsRevoked, and UnsafeAbortBufferedRecords allows for forcefully dropping anything being produced (albeit with documented caveats and downsides)

The client now guards against a broker that advertises FetchRequest v13+ (which only uses TopicIDs) but does not actually return / use TopicIDs. If you have an old IBP configured, the broker will not use TopicIDs even if the broker indicates it should. The client will now pin fetching to a max version of 12 if a topic has no TopicID.

The client now sets a record's Topic field earlier to DefaultProduceTopic, which allows the Topic field to be known present (or known non-present) in the OnRecordBuffered hook.

Lastly, we now universally use Go 1.19 atomic types if compiled with 1.19+. Go uses compiler intrinsics to ensure proper int64 / uint64 alignment within structs for the atomic types; Go does not ensure plain int64 / uint64 are properly aligned. A lot of work previously went into ensuring alignment and having a GitHub workflow that ran go vet on qemu armv7 emulation, but apparently that was not comprehensive enough. Now, if you use a 32 bit arch, it is recommended to just compile with 1.19+.

• d1b6897 feature kgo: add UnsafeAbortBufferedRecords
• d0c42ad improvement kgo source: do not use fetch topic IDs if the broker returns no ID
• cc3a355 and a2c4bad improvement kgo: universally switch to 1.19's atomics if on Go 1.19+
• 66e626f producer: set Record.Topic earlier
• 3186e61 feature kgo: add MarkedOffsets function

v1.10.4

This patch release fixes two bugs introduced with v1.10.0. These bugs are not encountered in when using the client to simply consume or produce. Only admin usages of the client may encounter the bugs this patch is fixing.

v1.10.0 introduced support for batch offset fetching or coordinator finding. These changes introduced a bug where empty coordinator keys (i.e., group names or transactional IDs) would be stripped from requests, and then a field in a nil pointer could be accessed and panic the program. These changes also introduced a bug that did not properly mirror one field for batched FindCoordinator requests.

• ca67da4 bugfix kgo: fix batch coordinator fetching
• c6f7f9a bugfix kgo: allow empty groups when finding coordinator / fetching offsets

v1.10.3

This small patch release is another attempted fix at #239. It is only possible to encounter this bug if a broker completely dies and never comes back, and you do not replace the broker (i.e., broker 3 dies and it is just gone forever).

Previously, kgo would cache the broker controller until NOT_CONTROLLER is seen. We now clear it a bit more widely, but this is just extra defensive behavior: the controller is updated on every metadata request.

Worse however, kgo previously cached group or transactional-id coordinators until COORDINATOR_NOT_AVAILABLE, COORDINATOR_LOAD_IN_PROGRESS, or NOT_CONTROLLER were seen. If the coordinator outright died and never comes back and is never replaced, all coordinator requests to that specific coordinator would fail.

Now, if we fail to dial the coordinator or controller 3x in a row, we delete the coordinator or controller to force a reload on the next retry. We only do this for dial errors because any other error means we actually contacted the broker and it exists.

Lastly, we change the default max produce record batch bytes from 1,000,000 to 1,000,012, to exactly mirror Kafka's max.message.bytes.

• e2e80bf kgo: clear controller/coordinator caches on failed dials

v1.10.2

This patch release contains one very minor bug fix, tightens a failure scenario, adds two missing errors to kerr, fixes a build constraint, and has a few internal style fixes from @PleasingFungus (thanks!).

The bug was introduced in v1.9.0 through a patch that fixed a potential spin loop. In fixing the spin loop, I inadvertently caused consumer fetch sessions to reset when there is no more data to consume. In your application, this would show up as more frequent metadata updates and up to 100ms of extra latency when there is new data to consume.

The tightened failure scenario allows records to be failed in more cases. Previously, as soon as a record was added to a produce request internally, the record could not be failed until a produce response is received. This behavior exists for duplicate prevention. However, there is a period of time between a produce request being created and actually being written, and if an AddPartitionsToTxn request takes a long time and then fails, the produce request would never be written and the records could never be failed. The tightened failure scenario allows records to be failed all the way up until they are actually serialized and written.

• d620765 sink: tighten canFailFromLoadErrs
• 6c0abd1 minor bugfix source: avoid backoff / session reset when there is no consumed data
• 6ce8bdf kerr: add two missing errors to ErrorForCode
• PR #264 fix isNetClosedErr build constraints: franz-go was using the strings.Contains version, which was meant for Go 1.15 only (thanks @PleasingFungus!)

v1.10.1

This patch release contains minor kgo internal improvements, and enables a new API for kadm. This patch contains no bug fixes. This patch should help recover faster if a transaction coordinator goes down while producing.

This is released in tandem with kadm v1.6.0, which contains a small kadm bugfix for DeleteRecords, OffsetForLeaderEpoch, and DescribeProducers, and (hopefully) finishes support for all current admin APIs.

• 56fcfb4 sink: log all aspects of wanting to / failing records
• 9ee5efa sink: update metadata when AddPartitionsToTxn fails repeatedly
• bc6810d broker: hide retryable errors once
• 83f0dbe kgo: add support for sharding WriteTxnMarkers

v1.10.0

This is a small release that contains one bug fix, one new feature, and improvements in log lines, and improvements to work around AWS MSK being a bit odd with SASL reauthentication.

Previously, the client's sticky partitioners actually did not preserve stickiness because the client did not attach previous-partitions when rejoining the group. That is now fixed.

The new feature, ConsumePreferringLagFn, allows you to have some advanced reordering of how to consume. The recommended way of using this option is kgo.ConsumePreferringLagFn(kgo.PreferLagAt(50)), which allows you to favor laggy partitions if the client is more than 50 records behind in the topic.

The kadm module is also released with v1.4.0, which contains new APIs to find coordinators for groups or transactional IDs, and an API to fetch API versions for all brokers in the cluster.

• a995b1b kgo broker: retry sasl auth failures during reauthentication
• 8ab8074 kgo connection: always allow one request after SASL
• dcfcacb bugfix {Cooperative,Sticky}Balancer: bug fix lack of stickiness
• 76430a8 feature kgo: add ConsumePreferringLagFn to consume preferring laggy partitions
• 9ac6c97 improvement kgo: support forward & backward batch requests for FindCoordinator, OffsetFetch

v1.9.1

This is a small patch release to work around two behavior problems, one with AWS and one with Redpanda. This is not an important bug release if you are using this library against Kafka itself.

For AWS, AWS is unexpectedly expiring certain permissions before the SASL lifetime is up. This manifests as GROUP_AUTHORIZATION_ERROR while consuming. Previously, we the client would mark connections to reauthenticate when the connection was within 3s of SASL expiry. We now are more pessimistic and reauthenticate within 95% to 98% of the lifetime, with a 2s minimum. This is similar to the Java client, which has always used 85 to 95% of the SASL lifetime and has no minimum.

For Redpanda, Redpanda's transaction support is nearly complete (v22.3 release imminent), but Redpanda can return UNKNOWN_SERVER_ERROR a bit more than Kafka does. These errors are being ironed out, but there is no harm in the client to pre-emptively handling these as retryable.

• 3ecaff2 kgo txn: handle UNKNOWN_SERVER_ERROR more widely
• eb6e3b5 kgo sasl reauth: be more pessimistic

v1.9.0

This release contains one important bugfix (sequence number int32 overflow) for long-lived producers, one minor bugfix that allows this client to work on 32 bit systems, and a few other small improvements.

This project now has integration tests ran on every PR (and it is now forbidden to push directly to master). These integration tests run against Kraft (Kafka + Raft), which itself seems to not be 100% polished. A good amount of investigation went into hardening the client internals to not fail when Kraft is going sideways.

This release also improves behavior when a consumer group leader using an instance ID restarts and changes the topics it wants to consume from. See the KIP-814 commit for more details.

It is now easier to setup a TLS dialer with a custom dial timeout, it is easier to detect if requests are failing due to missing SASL, and it is now possible to print attributes with RecordFormatter.

Lastly, the corresponding kadm v1.3.0 release adds new LeaveGroup admin APIs.

franz-go

• b18341d kgo: work around KIP-814 limitations
• 6cac810 kversions: bump Stable from 3.0 to 3.3
• PR #227 bugfix further sequence number overflows fix (thanks @ladislavmacoun!)
• PR #223 add GitHub actions integration test (thanks @mihaitodor!) and PR #224 fixup kgo guts to work around new kraft failures
• 203a837 franz-go: fix 32 bit alignment, fix a few lints
• 719c6f4 kgo: avoid overflow on 32 bit systems
• db5c159 feature kgo: add DialTimeout function, complementing DialTLSConfig
• b4aebf4 kgo: add ErrFirstReadEOF, which unwraps to io.EOF
• bbac68b RecordFormatter: support %a; formatter&reader: support 'bool'

kadm

• d3ee144 kadm: add LeaveGroup api
• 7b8d404 kadm: ListOffsetsAfterMill(future) should return end offsets

v1.8.0

This feature release adds one new API in kgo, one new field on kgo.Record, and stabilizes kversion.V3_3_0(). There is also one minor bug fix: Record.TimestampType() previously did not correctly return 1 to indicate broker generated timestamp types.

This release improves the behavior of the client if the entire cluster becomes unreachable. Previously, the client may not have been able to reload metadata to discover new endpoints; now, the client periodically tries a seed broker to issue randomly-routable requests to. This release also makes a few more internal errors retryable, which can help reduce some request failures.

A few docs have been improved. Notably, the UniformBytesPartitioner contains a new line describing that it may have poor interaction with lingering. See the doc comment for more details as well as the linked Kafka issue. This library does not use lingering by default.

• f35ef66 make errUnknown{Controller,Coordinator} retryable, improve error wording
• 750bf54 kversion: stabilize v3.3
• 3e02574 kgo: occasionally use seed brokers when choosing "random" brokers
• 3ebd775 UniformBytesPartitioner: note sub-optimal batches with lingering
• PR #206 bugfix Record.TimestampType function to correctly return 1 for broker-set timestamps (thanks @JacobSMoller)
• PR #201 feature add Context field to Record to enable more end-user instrumentation (thanks @yianni)
• PR #197 feature add ValidateOpts to validate options before client initialization (thanks @dwagin)

v1.7.1

This release fixes two bugs, one that is obscure and unlikely to be ran into in most use cases, and one that is not as obsure and may be ran into in a racy scenario. It is recommended to upgrade.

3191842 fixes a bug that could eventually lead to a completely stalled consumer. The problem can happen whenever an internal "consumer session" is stopped and restarted -- which happens on most rebalances, and happens whenever a partition moves from one broker to another. This logic race required no active fetches to be in flight nor buffered, and required a fetch to just about be issued.

0ca6478 fixes a complicated bug that could result in a panic. It requires the following:

• using a single client to produce and consume to the
• consuming from that topic first
• producing to that topic after the first consume
• the metadata load that is triggered from the produce fails with partition errors
• the metadata load retry moves a previously-errored partition from one broker to another

Any deviation from this sequence of events would not result in a panic. If the final step did not move the partition between brokers, the client would still be internally problematic, but there would be no visible problem (the partition would be produced to two brokers, the produce to the wrong broker would fail while the correct broker would succeed),

Relevant commits

• 0ca6478 kgo: avoid pointer reuse in metadata across producers & consumers
• 3191842 consumer: bugfix fetch concurrency loop
• 5f24fae kgo: fix an incorrect log line, add another log line

v1.7.0

This feature release adds a few new APIs to expose more information in the client or make some things simpler. There are also two minor bug fixes: manually committing a topic with no partitions would previously result in an error, and we previously did not properly load the partition leader epochs for a brief period of time when the client started which prevented truncation detection. See the commits below for more details.

• 3a229d9 kgo.Fetches: add Err0
• 5dd3321 kgo.EpochOffset: export Less, add docs
• 2b38ec5 kgo: add CloseAllowingRebalance
• ac2f97b kgo.Client: add GroupMetadata, ProducerID, PartitionLeader functions
• 9497cf3 minor bugfix kgo client.go: bugfix -1 leader epoch for a few minutes
• 11e3277 bugfix consumer groups: do not commit empty topics
• 52126de kgo: add optional interface to close sasls on client close
• #193 minor logging bugfix Use correct error in debug log for request failure (thanks @keitwb)
• #191 Add Fetches.NumRecords(), Fetches.Empty() (thanks @un000)
• 669a761 kerr: add two new errors

Also recently and newly released:

• pkg/kmsg v1.2.0, adding protocol support for new incoming KIPs.
• pkg/kadm v1.2.1, removing sorting from metadata response replica fields (v1.2 added new helpers)
• pkg/sasl/kerberos v1.1.0, making it easier to persist and shutdown the Kerberos client

v1.6.0

This release contains two new APIs, a minor bugfix, and other notable improvements and stabilizations.

The kadm package is now stabilized as a separate, v1.0 module. This module will remain separate from the top level franz-go so that it can have independent minor releases, and has more freedom to have major version bumps if necessary. I took stabilization as an opportunity to break & fix some infrequently used APIs; this can be seen in the commit linked below.

I have also created a new package for the schema registry, sr. This will likely live as a separate module for similar reasons to kmsg and kadm: to have more freedom to make major-version-changing breaking changes if Confluent decides to change some of their HTTP API. I expect to stabilize sr once I know of at least one use case that helps double check the API is alright.

Bugfix

Previously, if you consumed a topic that had record timestamps generated by the broker per LogAppendTime, this client would not set the timestamp properly when consumed. We now set the timestamp properly.

Improvements

The client now allows the user to set a timestamp when producing: if a record's timestamp is non-zero, the client will not override it.

The default partitioner has been changed to the new UniformBytesPartitioner. This is an improvement on the previous StickyKeyPartitioner in a few ways and can be read about in KIP-794. The implementation in this client is slightly different from KIP-794 in ways that are documented on the UniformBytesPartitioner itself. This new partitioner can result in more balanced load over a long period of producing to your brokers. Note: the new default partitioner partitions keys the same as the old default partitioner, so this is not a behavior change.

Features

• UniformBytesPartitioner exists, which can be used for more balanced producing over long time periods. The default batch size switch is 64KiB, and you may want to tune this up or down if you produce in high or low throughput.

• kversion.V3_2_0() now officially exists, and kversion correctly detects v3.2 brokers.

• kmsg has a new UnsafeReadFrom interface to help reduce garbage in some advanced scenarios (requires [email protected]).

Relevant commits

• b279658 kadm: break APIs for 1.0
• a23a076 bugfix source: properly set Timestamp for LogAppendTime records
• 653010d improvement producer: allow the user to set Timestamp
• d53c0fe feature kmsg: add new UnsafeReadFrom interface
• 5536ec1 feature kversion: add V3_2_0
• 0f65bb1 feature kgo: expose UniformBytesPartitioner
• 82af4a1 and followup commits: add package sr, providing a client for the schema registry

v1.5.3

This bugfix release fixes a problem I noticed when reading Kafka source code last week. KIP-98 never specified what a sequence number wrapping meant when producing with idempotency enabled / with transactions, so I implemented this to wrap to negative. As it turns out, there is validation in the Kafka code that the sequence number must wrap to 0.

Thus, using this client, if an application produced 2**31 records to a single partition with idempotent production or with transactions without restarting, this client would enter a fatal state.

I'm not sure how common this use case is considering this bug has not been reported in 2 years, but this patch release is to ensure people do not encounter this bug after this point.

I've tested this by producing >2.147bil records to a single-partition Kafka topic before this patch, which eventually results in INVALID_RECORD errors, and then producing >2.2 records to a single-partition Kafka topic after this patch. The patch allows the client to produce indefinitely.

This release also includes a few commits that eliminate two external dependencies, and contains a patch in kadm to avoid a panic on nil input to a function.

• 4e2fa3f sticky: vendor go-rbtree, drop external dep
• 6c0756d drop go-cmp dep
• 27880b4 bugfix sink: sequence number wrapping for EOS
• afc9017 kadm.CalculateGroupLag: avoid panic if input maps are nil

v1.5.2

This tiny release contains another fix for RecordReader, specifically for regex parsing, and changes the behavior of MarkCommitRecords to its original behavior.

• For RecordReader, the regex type was not properly registered everywhere internally. This resulted in %v{re#...#}\n trying to parse a newline as part of the regex, rather than as a delimiter. This is fixed and a test case added. Note that this feature is niche and new, so this is a very minor bug.

• For MarkCommitRecords, v1.3.3 changed the behavior to allow rewinds. This is difficult to reason about and can result in bugs. More likely, you just want to periodically mark to move forward; the behavior now is more in line with what people expect.

• ff5a3ed MarkCommitRecords: forbid rewinds
• 41284b3 RecordReader: fix regex reading even more

v1.5.1

This release fixes a minor bug in RecordReader, and has a behavior change for polling records (and a corresponding tiny new helper API for this).

For the bugfix, RecordReader did not always properly return io.ErrUnexpectedEOF. We now return it more properly and add tests for the missing edge cases.

For the behavior change, we now inject an error into PollFetches and PollRecords if the user context is canceled. Previously, we would just quit the poll and return. This change introduces a new corresponding function, Fetches.Err() error. The thought here is that now we have more injected errors, so Fetches.Err can make it easier to check various errors.

• cbc8962 behavior change Poll{Records,Fetches}: inject an error for canceled context
• #163 docs: updates StickyBalancer godoc (thanks @Streppel)
• 2018d20 bugfix RecordReader: properly return io.ErrUnexpectedEOF
• #161 examples: avoid duplicated module name (thanks @robsonpeixoto)

v1.5.0

This release adds a few new APIs, has a few small behavior changes, and has one "breaking" change.

Breaking changes

The kerberos package is now a dedicated separate module. Rather than requiring a major version bump, since this fix is entirely at the module level for an almost entirely unused package, I figured it is okayish to technically break compatibility for the few usages of this package, when the fix can be done entirely when go geting.

The gokrb5 library, basically the only library in the Go ecosystem that implements Kerberos, has a slightly broken license. Organizations that are sensitive to this were required to not use franz-go even if they did not use Kerberos because franz-go pulls in a dependency on gokrb5.

Now, with kerberos being a distinct and separate module, depending on franz-go only will not cause an indirect dependency on gokrb5.

If your upgrade is broken by this change, run:

go get github.com/twmb/franz-go/pkg/sasl/kerberos@v1.0.0
go get github.com/twmb/franz-go@v1.5.0

Behavior changes

• UnknownTopicRetries now allows -1 to signal disabling the option (meaning unlimited retries, rather than no retries). This follows the convention of other options where -1 disables limits.

Improvements

• Waiting for unknown topics while producing now takes into account both the produce context and aborting. Previously, the record context was only taken into account after a topic was loaded. The same is true for aborting buffered records: previously, abort would hang until a topic was loaded.

• New APIs are added to kmsg to deprecate the previous Into functions. The Into functions still exist and will not be removed until kadm is stabilized (see #141).

Features

• ConsumeResetOffset is now clearer, you can now use NoResetOffset with start or end or exact offsets, and there is now the very useful Offset.AfterMilli function. Previously, NoResetOffset only allowed starting consuming at the start and it was not obvious why. We keep the previous default-to-start behavior, but we now allow modifying it. As well, AfterMilli can be used to largely replace AtEnd. Odds are, you want to consume all records after your program starts even if new partitions are added to a topic. Previously, if you added a partition to a topic, AtEnd would miss records that were produced until the client refreshed metadata and discovered the partition. Because of this, you were safer using AtStart, but this unnecessarily forced you to consume everything on program start.

• Custom group balancers can now return errors, you can now intercept commits to attach metadata, and you can now intercept offset fetches to read metadata. Previously, none of this was possible. I considered metadata a bit of a niche feature, but accessing it (as well as returning errors when balancing) is required if you want to implement streams. New APIs now exist to support the more advanced behavior: PreCommitFnContext, OnOffsetsFetched, and GroupMemberBalancerOrError. As well, BalancePlan.AsMemberIDMap now exists to provide access to a plan's underlying plan map. This did not exist previously because I wanted to keep the type opaque for potential future changes, but the odds of this are low and we can attempt forward compatibility when the time arises.

• RecordReader now supports regular expressions for text values.

Relevant commits

• a2cbbf8 go.{mod,sum}: go get -u ./...; go mod tidy
• ce7a84f kerberos: split into dedicated module, p1
• e8e5c82 and 744a60e kgo: improve ConsumeResetOffset, NoResetOffset, add Offset.AfterMilli
• 78fff0f and e8e5117 and b457742: add GroupMemberBalancerOrError
• b5256c7 kadm: fix long standing poor API (Into fns)
• 8148c55 BalancePlan: add AsMemberIDMap
• 113a2c0 add OnOffsetsFetched function to allow inspecting commit metadata
• 0a4f2ec and cba9e26 kgo: add PreCommitFnContext, enabling pre-commit interceptors for metadata
• 42e5b57 producer: allow a canceled context & aborting to quit unknown wait
• 96d647a UnknownTopicRetries: allow -1 to disable the option
• 001c6d3 RecordReader: support regular expressions for text values

v1.4.2

This release fixes a potential incremental fetch session spin loop / undesirable behavior. This was not reported, but can happen if you use many clients against your cluster.

Previously, if a broker advertised that it supported consumer fetch sessions but did not actually create any and returned "0" to signify no session was created, the client would accept that 0 as a new fetch session. If the fetch response returned no data and thus made no forward progress, the next fetch request would include no partitions (believing a fetch session was created), and the broker would again reply immediately with no data and no fetch session. This would loop. Now, if the broker indicates no fetch session was created, we immediately stop trying to create new fetch sessions and never try again.

In practice, fetch sessions are rejected if and replied to with 0 if a new one cannot be created. The default fetch session cache in Kafka is 1,000. If you have more than 1,000 active clients (where brokers count as clients against other brokers), you are at risk of this bug.

This bug would manifest in clearly visible ways: higher cpu, no forward progress while consuming. If you have not seen these, you have not experienced the bug. However, it is recommended that all users upgrade to avoid it.

This has two followup fixes to 83b0a32, one which fixes behavior that broke EndBeginTxnSafe, and one which mirrors some of the logic supporting EndBeginTxnUnsafe into EndTransaction itself. This also fixes a very rare data race that realistically would result in a new connection being killed immediately (since at the CPU, reads/writes of pointers is atomic).

• 2faf459 bugfix broker: fix rare data race
• 8f7c8cd bugfix EndBeginTxnUnsafe: partially back out of 83b0a32
• 85a680e bugfix consuming: do not continually try to create fetch sessions
• 2decd27 bugfix EndTransaction: mirror EndBeginTxnUnsafe logic

v1.4.1

This release pins kmsg to its newly stable version v1.0.0, fixing a compilation issue for anybody doing go get -u.

The kmsg package was previously unversioned because Kafka sometimes changes the protocol in such a way that breaks the API as chosen in kmsg (plain types, not objects for everything). The most recent change in kmsg to match a recent type rename in Kafka broke kgo because kgo depended on the old name. Again, this was not pinned because franz-go did not depend on a specific version of kmsg. To prevent this issue from happening again, we now pin to a stable kmsg version.

There are also two small bugfixes and a few improvements. Previously, ProducerFenced was marked as retriable, which could result in the client internally entering a fatal state that the user was unaware of. This should now be bubbled up. As well, there were a few subtle issues with EndBeginTxnUnsafe that have been addressed.

Notable commits & PRs:

• 83b0a32 bugfix kgo: EndAndBeginTransaction w/ EndBeginTxnUnsafe: fix three issues
• bd1d43d sink: small AddPartitionsToTxn improvements
• 65ca0bd bugfix kerr: ProducerFenced is not retriable
• PR #148 lower FetchMaxPartitionBytes to 1MiB to be in line with the Kafka default (thanks @jcsp)
• 806cf53 feature kmsg: add TextMarshaler/TextUnmarshaler to enums
• 49f678d update deps, pulling in klauspost/compress v1.15.1 which makes zstd encoding & decoding stateless

v1.4.0

This release adds a lot of new features and changes a few internal behaviors. The new features have been tested, but it is possible that a bug slipped by—if you see one, please open an issue and the bug can be fixed promptly.

Behavior changes

• Promises are now serialized. Previously, promises were called at the end of handling produce requests. As well, errors that caused records to fail independent of producing could fail whenever. Now, all promises are called in one loop. Benchmarking showed that concurrent promises did not really help, even in cases where the promises could be concurrent. As well, my guess is that most people serialize promises, resulting in more complicated logic punted to the users. Now with serializing promises, user code can be simpler.

• The default MetadataMinAge has been lowered from 5s to 2.5s. Metadata refreshes internally on retryable errors, 2.5s helps fail records for non-existing topics quicker. Related, for sharded requests, we now cache topic & partition metadata for the MetadataMinAge. This mostly benefits ListOffsets, where usually a person may list both the start and end back to back. We cannot cache indefinitely because a user may add partitions outside this client, but 2.5s is still helpful especially for how infrequently sharded requests are issued.

• Group leaders now track topics that the leader is not interested in consuming. Previously, if leader A consumed only topic foo and member B only bar, then leader A would not notice if partitions were added to bar. Now, the leader tracks bar. This behavior change only affects groups where the members consume non-overlapping topics.

• Group joins & leaves now include a reason, as per KIP-800. This will be useful when Kafka 3.2 is released.

• Transactions no longer log CONCURRENT_TRANSACTIONS errors at the info level. This was a noisy log that meant nothing and was non-actionable. We still track this at the debug level.

Features

A few new APIs and options have been added. These will be described shortly here, and the commits are linked below.

• ConcurrentTransactionsBackoff: a new option that allows configuring the backoff when starting a transaction runs into the CONCURRENT_TRANSACTIONS error. Changing the backoff can decrease latency if Kafka is fast, but can increase load on the cluster.

• MaxProduceRequestsInflightPerBroker: a new option that allows changing the max inflight produce requests per broker if you disable idempotency. Idempotency has an upper bound of 5 requests; by default, disabling idempotency sets the max inflight to 1.

• UnknownTopicRetries: a new option that sets how many times a metadata load for a topic can return UNKNOWN_TOPIC_OR_PARTITION before all records buffered for the topic are failed. As well, we now use this option more widely: if a topic is loaded successfully and then later repeatedly experiences these errors, records will be failed. Previously, this limit was internal and was only applied before the topic was loaded successfully once.

• NoResetOffset: a new special offset that can be used with ConsumeResetOffset to trigger the client to enter a fatal state if OffsetOutOfRange is encountered.

• Client.PurgeTopicsFromClient: a new API that allows for completely removing a topic from the client. This can help if you regex consume and delete a topic, or if you produce to random topics and then stop producing to some of them.

• Client.AddConsumeTopics: a new API that enables you to consume from topics that you did not initially configure. This enables you to add more topics to consume from without restarting the client; this works both both direct consumers and group consumers.

• Client.TryProduce: a new API that is a truly non-blocking produce. If the client has the maximum amount of records buffered, this function will immediately fail a new promise with ErrMaxBuffered.

• Client.ForceMetadataRefresh: a new API that allows you to manually trigger a metadata refresh. This can be useful if you added partitions to a topic and want to trigger a metadata refresh to load those partitions sooner than the default MetadataMaxAge refresh interval.

• Client.EndAndBeginTransaction: a new API that can be used to have higher throughput when producing transactionally. This API requires care; if you use it, read the documentation for what it provides and any downsides.

• BlockRebalancesOnPoll and Client.AllowRebalance: a new option and corresponding required API that allows for easier reasoning about when rebalances can happen. This option can be greatly beneficial to users for simplifying code, but has a risk around taking so long that your group member is booted from the group. Two examples were added using these options.

• kversion.V3_1_0: the kversion package now officially detects v3.1 and has an API for it.

Relevant commits

• PR #137 and c3fc8e0: add two more goroutine per consumer examples (thanks @JacobSMoller)
• cffbee7 consumer: add BlockRebalancesOnPoll option, AllowRebalance (commit accidentally pluralized)
• 39af436 docs: add metrics-and-logging.md
• 83dfa9d client: add EndAndBeginTransaction
• d11066f committing: internally retry on some errors when cooperative
• 31f3f5f producer: serialize promises
• e3ef142 txn: move concurrent transactions log to debug level
• 10ee8dd group consuming: add reasons to JoinGroup, LeaveGroup per KIP-800
• 0bfaf64 consumer group: track topics that the leader is not interested in
• e8495bb client: add ForceMetadataRefresh
• c763c9b consuming: add NoResetOffset
• 4e0e1d7 config: add UnknownTopicRetries option, use more widely
• 7f58a97 config: lower default MetadataMinAge to 2.5s
• e7bd28f Client,GroupTransactSession: add TryProduce
• 2a2cf66 consumer: add AddConsumeTopics
• d178e26 client: add PurgeTopicsFromClient
• 336d2c9 kgo: add ConcurrentTransactionsBackoff, MaxProduceRequestsInflightPerBroker
• fb04711 kversion: cut v3.1

v1.3.5

This patch release fixes a panic in GroupTransactSession.End and has three behavior changes that are beneficial to users. The panic was introduced in v1.3.0; if using a GroupTransactSession, it is recommended you upgrade to this release.

The next release aims to be v1.4.0, this release is a small one to address a few issues before the much larger and feature filled v1.4 release.

• 010e8e1 txn: fix panic in GroupTransactSession.End
• f9cd625 consuming: handle exact offset consuming better
• 2ab1978 EndTransaction: return nil rather than an error if not in a transaction
• 96bfe52 broker: remove 5s minimum for sasl session lifetime

v1.3.4

This small patch release fixes a problem with 4f2e7fe3 which was meant to address #98. The fix was not complete in that the fix would only trigger if a group member had partitions added to it. We now rearrange the logic such that it occurs always. This bug was found while making a change in the code in support of a new feature in the v1.4 branch; this bug was not encountered in production.

This also bumps the franz-go/pkg/kmsg dependency so that JoinGroup.Reason is properly tagged as v9+.

The next release will be v1.4, which is nearly ready to be merged into this branch and tagged. Follow issue #135 for more details.

• 02560c7 consumer group: bugfix fetch offsets spanning rebalance

v1.3.3

This patch release contains two minor bug fixes and a few small behavior changes. The upcoming v1.4 release will contain more changes to lint the entire codebase and will have a few new options as features to configure the client internals. There are a few features in development yet that I would like to complete before tagging the next minor release.

Bug fixes

Repeated integration testing resulted in a rare data race, and one other bug was found by linting. For the race, if a group was left or heartbeating stopped before offset fetching finished, then there would be a concurrent double write to an error variable: one write would try to write an error from the request being cut (which would be context.Canceled), and the other write would write the same error, but directly from ctx.Err. Since both of these are the same type pointer and data pointer, it is unlikely this race would result in anything if it was ever encountered, and encountering it would be rare.

For the second bug, after this prior one, I wondered if any linter would have caught this bug (the answer is no). However, in the process of heavily linting the code base, a separate bug was found. This bug has no impact, but it is good to fix. If you previously consumed and specified exact offsets to consume from, the internal ListOffsets request would use that offset as a timestamp, rather than using -1 as I meant to internally. The whole point is just to load the partition, so using a random number for a timestmap is just as good as using -1, but we may as well use -1 to be proper.

Behavior changes

Previously when producing, the buffer draining goroutine would sleep for 50ms whenever it started. This was done to give high throughput producers a chance to produce more records within the first batch, rather than the loop being so fast that one record is in the first batch (and more in the others). This 50ms sleep is a huge penalty to oneshot producers (producing one message at a time, synchronously) and also was a slight penalty to high throughput producers whenever the drain loop quit and needed to be resumed. We now eliminate this sleep. This may result in more smaller batches, but definitely helps oneshot producers. A linger can be used to avoid small batches, if needed.

Previously, due to MS Azure improperly replying to produce requests when acks were zero, a discard goroutine was added to drain the produce connection if the client was configured to produce with no acks. Logic has been added to quit this goroutine if nothing is read on that goroutine for 3x the connection timeout overhead, which is well enough time that a response should be received if the broker is ever going to send one.

Previously, MarkCommitRecords would forbid rewinds and only allow advancing offsets. The code now allows rewinds if you mark an early offset after you have already marked a later offset. This brings the behavior in line with the current CommitOffsets.

Previously, if the client encountered CONCURRENT_TRANSACTIONS during transactions, it would sleep for 100ms and then retry the relevant request. This sleep has been dropped to 20ms, which should help latency when transacting quickly. The v1.4 release will allow this number to be configured with a new option.

Additions

KIP-784 and KIP-814 are now supported (unreleased yet in Kafka). Support for KIP-814 required bumping the franz-go's kmsg dep. Internally, only KIP-814 affects client behavior, but since this is unrelased, it is not changing any behavior.

Relevant commits

• b39ca31 fetchOffsets: fix data race
• 4156e9f kgo: fix one bug found by linting
• 72760bf..ad991d8 kmsg, kversion, kgo: support KIP-814 (SkipAssignment in JoinGroupResponse)
• db9017a broker: allow the acks==0 producing discard goroutine to die
• eefb1f3 consuming: update docs & simplify; MarkCommitRecords: allow rewinds
• 8808b94 sink: remove 50ms wait on new drain loops
• a13f918 kmsg & kversion: add support for KIP-784 (ErrorCode in DescribeLogDirs response)
• PR #133 - lower concurrent transactions retry to 20ms; configurability will be in the next release (thanks @eduard-netsajev)

v1.3.2

This patch fixes a bug of unclear severity related to transactions. Credit goes to @eduard-netsajev for finding this long standing problem.

In Kafka, if you try to start a transaction too soon after finishing the previous one, Kafka may not actually have internally finished the prior transaction yet and can return a CONCURRENT_TRANSACTIONS error. To work around this, clients are expected to retry when they see this error (even though it is marked as not retriable).

This client does that properly, but unfortunately did not bubble up any non CONCURRENT_TRANSACTIONS errors.

From the code, it appears as if in the worst case, this could have meant that transactions invisibly looked like they were working and being used when they actually were not. However, it's likely that other errors would be noticed internally, and it's possible that if you encountered problems, the entire ETL pipeline would stall anyway.

All told, it's not entirely clear what the ramifications for this bug are, and it is recommended that if you use transactions, you should update immediately.

• PR #131 - txns: don't ignore error in doWithConcurrentTransactions

v1.3.1

This small patch release fixes a leaked-goroutine problem after closing a consuming client, and adds one config validation to hopefully reduce confusion.

For the bug, if a fetch was buffered when you were closing the client, an internal goroutine would stay alive. In normal cases where you have one client in your program and you close it on program shutdown, this leak is not really important. If your program recreates consuming clients often and stays alive, the leaked goroutine could eventually result in unexpected memory consumption. Now, the client internally unbuffers all fetches at the end of Close, which allows the previously-leaking goroutine to exit.

For the config validation, using ConsumePartitions and ConsumeTopics with the same topic in both options would silently ignore the topic in ConsumePartitions. Now, the client will return an error that using the same topic in both options is invalid.

• ea11266 config: add duplicately specified topic validation
• bb581f4 bugfix client: unbuffer fetches on Close to allow mangeFetchConcurrency to quit

v1.3.0

This release contains three new features, a few behavior changes, and one minor bugfix.

For features, you can now adjust fetched offsets before they are used (thanks @michaelwilner!), you can now "ping" your cluster to see if the client can connect at all, and you can now use SetOffsets when consuming partitions manually. As a somewhat of a feature-ish, producing no longer requires a context, instead if a context is nil, context.Background is used (this was added to allow more laziness when writing small unimportant files).

The transactional behavior change is important: the documentation changes are worth reading, and it is worth using a 2.5+ cluster along with the RequireStableFetchOffsets option if possible. The metadata leader epoch rewinding behavior change allows the client to continue in the event of odd cluster issues.

In kadm, we now return individual per-partition errors if partitions are not included in OffsetCommit responses. The generated code now has a few more enums (thanks @weeco!)

Lastly, as a small bugfix, client.Close() did not properly stop seed brokers. A previous commit split seed brokers and non-seed brokers internally into two fields but did not add broker shutdown on the now-split seed broker field.

• e0b520c behavior change kadm: set per-partition errors on missing offsets in CommitOffsets
• 32425df feature client: add Ping method
• a059901 behavior change txns: sleep 200ms on commit, preventing rebalance / new commit
• 12eaa1e behavior change metadata: allow leader epoch rewinds after 5 tries
• 029e655 feature-ish Produce{,Sync}: default to context.Background if no ctx is provided
• eb2cec3 bugfix client: stop seed brokers on client.Close
• 2eae20d feature consumer: allow SetOffsets for direct partition consuming
• pr #120 feature Add groupopt to swizzle offset assignments before consumption (thanks @michaelwilner!)

v1.2.6

This patch release contains a behavior change to immediate metadata triggers to better support some loading error conditions and drops the default MetadataMinAge from 10s to 5s. For more details, see commit 8325ba7 or issue 114.

This release also contains a bugfix for using preferred read replicas. Previously, if a replica was not the leader of any partition being consumed, the client would not internally save knowledge of that replica and it could not be consumed from. This would result in the client ping-ponging trying to fetch from the leader and then erroring when the leader indicates the client should consume from a replica the client does not know about. This is no longer the case.

Lastly, this patch fixes the behavior of rotating through partitions while consuming. Previously, the client rotated through partitions to evaluate for consuming, but then saved those partitions to nested maps which had non-deterministic (and, due to how Go ranges, mostly not-that-random) range semantics. The client now always rotates through partitions and topics in the order the partitions are evaluated. The old behavior could theoretically lead to more starvation than necessary while consuming. The new behavior should have no starvation, but really due to the randomness of the prior behavior, the new semantics may be a wash. However, the new semantics are the original intended semantics.

• bc391a3 improvement source: rotate through topics/partitions as we fetch
• 6bbdaa2 bugfix client: create a sink & source for all partition replicas
• 8325ba7 behavior change metadata: minor changes, & wait a bit when looping for now triggers
• b8b7bd1 behavior change RecordFormatter: always use UTC
• 6ab9044 kadm: return defined errors for On functions

v1.2.5

This small patch release fixes one non-impacting bug in SCRAM authentication, and allows more errors to be abort&retryable rather than fatal while transactionally committing.

For SCRAM, this client did not implement the client-final-reply completely correctly: this client replied with just the client nonce, not the client nonce + server nonce. Technically this was not to spec, but no broker today enforces this final nonce correctly. However, the client has been fixed so that if someday brokers do start enforcing the nonce correctly, this client will be ready.

For transactional committing, we can handle a few extra errors while committing without entering a fatal state. Previously, ILLEGAL_GENERATION was handled: this meant that a rebalance began and completed before the client's commit went through. In this case, we just aborted the transaction and continued successfully. We can do this same thing for REBALANCE_IN_PROGRESS, which is similar to the prior error, as well as for errors that result from client request retry limits.

The integration tests now no longer depend on kcl, meaning you can simply go test in the kgo package to test against your local brokers. Seeds can be provided by specifying a KGO_SEEDS environment variable, otherwise the default is 127.0.0.1:9092.

Lastly, a few bugs have been fixed in the not-yet-stable, currently-separate-module kadm package. If you use that package, you may have already pulled in these fixes.

• 17dfae8 go.{mod,sum}: update deps
• 3b34db0 txn test: remove increasing-from-0 strictness when producing
• d0a27f3 testing: remove dependency on kcl
• 8edf934 txn: allow more commit errors to just trigger abort
• 03c58cb scram: use c-nonce s-nonce, not just c-nonce, in client-reply-final
• 8f34083 consumer group: avoid regex log if no topics were added/skipped

v1.2.4

This patch release fixes handling forgotten topics in fetch sessions, and allows disabling fetch sessions. Previously, if a topic or partition was paused with fetch sessions active, the partition would continually be fetched and skipped behind the scenes. As well, the client now allows disabling fetch sessions entirely if they are not desired.

This also fixes one bug in the RecordReader: using an empty layout would mean that any io.Reader would result in infinite messages.

Lastly, some log messages have been improved.

• db90100 consuming: improve error messages
• 101d6bd consuming: log added/skipped when consuming by regex
• b6759bc improvement consumer: allow disabling fetch sessions with a config opt
• 7cd959c bugfix source: use forgotten topics for sessions
• cfb4a7f bugfix kgo: error if RecordReader layout is empty

v1.2.3

This patch fixes the client not supporting brokers that start from large node IDs. The client previously assumed that brokers started at node ID 0 or 1 and went upwards from there. Starting at node 1000 would not always work.

This also adds two very tiny new APIs, FetchTopic.Each{Partition,Record}, which are so tiny they are not worth a minor release.

More work on kadm has been done: the package now supports ACLs.

SASL no longer has a hard coded 30s write timeout; instead, we use the RequestTimeoutOverhead same as everything else. The default produce request timeout has been dropped to 10s from 30s, which is still ~10x more time than Kafka usually needs at the p99.9 level. This will help speed up producing to hung brokers. As well, the default backoff has been changed to 250ms-2.5s rather than 100ms-1s. The old backoff retried too quickly in all cases.

Logs for assigned partitions have been improved, as have logs for inner metadata request / fetch request failures.

• 07a38bc bugfix client: support non-zero/one node IDs
• 3cbaa5f add more context to metadata reloads on inner partition errors
• 1bc1156 feature FetchTopic: add EachRecord, Records helper methods
• 0779837 consuming, group: improve logging, simplify code
• d378b32 config: edit comment for FetchMaxWait (about Java setting) (thanks @dwagin!)
• df80a52 behavior change config: drop ProduceRequestTimeout to 10s, doc more
• 6912cfe behavior change config: change default backoff from 100ms-1s to 250ms-2.5s
• c197efd behavior change client: remove 30s default write timeout for SASL
• 10ff785 metadata: drop timer based info log, reword

v1.2.2

This patch release fixes a bug with cooperative group consuming. If a cooperative group member rebalances before offset fetching returns, then it will not resume offset fetching partitions it kept across the rebalance. It will only offset fetch new partitions.

This release fixes that by tracking a bit of fetch state across rebalances for cooperative consumers. See the embedded comments in the commit for more details.

• 4f2e7fe bugfix consumer group: fix cooperative rebalancing losing offset fetches

v1.2.1

This patch release fixes a panic that can occur in the following sequence of events:

1. a LeaveGroup occurs (which always happens in Close)
2. the cluster moves a partition from one broker to another
3. a metadata refresh occurs and sees the partition has moved

Whenever a client closes, Close calls LeaveGroup (even if not in a group), and there is a small window of time before the metadata loop quits.

• 864526a bugfix consuming: avoid setting cursors to nil on LeaveGroup

v1.2.0

This release contains new formatting features and sets the stage for a new admin administration package to be added in v1.3.0. For now, the kadm package is in a separate unversioned module. The API is relatively stable, but I'd like to play with it some more to figure out what needs changing or not. Any external experimenting and feedback is welcome.

There are two new types introduced in the kgo package: RecordFormatter and RecordReader. Both of these extract and improve logic used in the kcl repo. These are effectively powerful ways to format records into bytes, and read bytes into records. They are not exactly opposites of each other due to reasons mentioned in the docs. I expect formatting to be more useful than reading, and formatting is actually surprisingly fast if the formatter is reused. The one off Record.AppendFormat builds a new formatter on each use and should only be used if needed infrequently, because building the formatter is the slow part.

I am considering removing the default of snappy compression for the v1.3 release. I generally find it useful: many people forget to add compression which increases network costs and makes broker disks fill faster, and snappy compression is cheap cpu-wise and fast. However, some people are confused when their bandwidth metrics look lower than they expect, and snappy does mean throughput is not as high as it could be. Removal of snappy by default may or may not happen, but if anybody agrees or disagrees with it, please mention so in an issue or on discord.

There are a few minor behavior changes in this release that should make default clients safer (lowering max buffered memory) and faster on request failures. These behavior changes should not affect anything. As well, the bench utility no longer uses snappy by default.

Non-formatter/reader/kadm commits worth mentioning:

• a8dbd2f broker: add context to responses that look like HTTP
• ec0d81f broker: avoid non-debug logs on ErrClientClosed
• af4fce4 beahvior change bench: use no compression by default, remove -no-compression flag
• d368d11 bench: allow custom certs with -ca-cert, -client-cert, -client-key
• fbf9239 broker: add two new connection types, cxnGroup and cxnSlow
• 2d6c1a8 behavior change client: lower RequestTimeoutOverhead and RetryTimeout defaults
• 9bcfc98 kgo: only run req/resp handling goroutines when needed
• b9b592e behavior change kgo: change default MaxBufferedRecords from unlimited to 10,000
• 19f4e9b and 58bf74a client: collapse shard errors
• 126778a client: avoid sharding to partitions with no leader
• 254764a behavior change kversion: skip WriteTxnMarkers for version guessing

v1.1.4

This includes on more patch for the prior tag to fully make InitProducerID retriable when it encounters a retriable error.

• d623ffe errors: make errProducerIDLoadFail retriable

v1.1.3

This patch allows BrokerNotAvailable to be retried. As well, it contains some small improvements under the hood. When sharding certain requests, we now avoid issuing requests to partitions that have no leader. We also better collapse per-partition sharding error messages.

Dial errors are now not retriable. Now, if a produce request fails because the broker cannot be dialed, we refresh metadata. Previously, we just accepted the error as retriable and tried producing again.

The SoftwareVersion used in ApiVersions requests now includes your current kgo version.

This tag is based on a 1.1.x branch in the repo. There is some feature work that is yet to be stabilized on the main branch.

Notable commits:

• 747ab0c kerr: make BrokerNotAvailable retriable
• f494301 errors: make dial errors non-retriable
• 4a76861 config: default to kgo dep version in ApiVersions

v1.1.2

This patch release fixes processing the LogAppendTime timestamp for message set v1 formatted records. Message set v1 records were used only during the Kafka v0.10 releases.

• 5fee169..688d6fb: bugfix message set v1: fix bit 4 as the timestamp bit

v1.1.1

This patch release fixes a bug in PollRecords that could cause a panic during cluster instability. This also defines Kafka 3.0 in kversion.

• 847aeb9 bugfix consumer: do not buffer partitions we reload
• 49f82b9 kversion: cut 3.0

v1.1.0

This minor release contains a few useful features, an incredibly minor bugfix (fixing an error message), and a behavior change around buffering produced records for unknown topics. As well, all plugins have been tagged v1.0.0.

• cf04997 errors: export ErrRecordRetries, ErrRecordTimeout
• ee8b12d producer: fail topics that repeatedly fail to load after 5 tries
• f6a8c9a very minor bugfix ErrDataLoss: use the new offset after we create the error
• 8216b7c and c153b9a feature kmsg: add EnumStrings(), ParseEnum() functions
• e44dde9 add goroutine_per_partition consuming example
• cedffb7 feature plugins: Add kzerolog logging adapter (thanks @fsaintjacques!)
• 563e016 feature FetchTopic: add EachPartition; FetchPartition: add EachRecord
• 8f648e7 consumer group: document actual behavior for on revoked / lost

v1.0.0

This is a significant release and is a commitment to not changing the API. There is no change in this release from v0.11.1. This release has been a long time coming!

The kmsg package is a separate dedicated module and its API can still change if Kafka changes the protocol in a way that breaks kmsg. However, the odds are increasingly likely that kmsg will switch to bumping major versions as Kafka makes incompatible changes, so that the module does not have breaking updates.

v0.11.1

This is a patch release to a bug introduced in v0.10.3 / v0.11.0.

The intent is to tag v1.0 either Friday (tomorrow) or Monday.

• 1469495 bugfix isRetriableBrokerErr: nil error is not retriable (thanks @Neal!)
• 33635e2 feature consumer: add pausing / unpausing topics and partitions
• 082db89 bugfix add locking to g.uncommitted MarkCommitRecords (thanks @vtolstov!)
• 3684df2 fetches: rename CollectRecords to Records

v0.11.0

This release is an rc2 for a v1 release, and contains breaking API changes related to renaming some options. The point of this release is to allow any chance for final API suggestions before stabilization.

The following configuration options were changed:

• ConnTimeoutOverhead to RequestTimeoutOverhead
• CommitCallback to AutoCommitCallback
• On{Assigned,Revoked,Lost} to OnPartitions{Assigned,LostRevoked}
• BatchCompression to ProducerBatchCompression
• Linger to ProducerLinger
• BatchMaxBytes to ProducerBatchMaxBytes
• {,Stop}OnDataLoss to {,Stop}ProducerOnDataLossDetected
• RecordTimeout to RecordDeliveryTimeout

The point of these renames is to make the options a bit clearer as to their purpose and to hopefully be slightly less confusing.

If you have any API suggestions that should be addressed before a 1.0 API stabilization release, please open an issue.

• 577c73a breaking: rename RecordTimeout to RecordDeliveryTimeout
• 76ae8f5 breaking: rename {,Stop}OnDataLoss to {,Stop}ProducerOnDataLossDetected
• 6272a3b breaking: rename BatchMaxBytes to ProducerBatchMaxBytes
• 9a76213 breaking: rename Linger to ProducerLinger
• 3d354bc breaking: rename BatchCompression to ProducerBatchCompression
• 8c3eb3c breaking: renaming OnXyz to OnPartitionsXyz
• 525b2d2 breaking: rename CommitCallback to AutoCommitCallback
• ac9fd1c docs: clarify Balancer is equivalent to Java's PartitionAssignor
• 2109ed4 breaking: rename ConnTimeoutOverhead to RequestTimeoutOverhead

v0.10.3

This is a small release intended to be a minor release for anybody that does not want to update the API. The next release, v0.11.0, is going to contain breaking config option changes. The point of the intermediate release is to allow a few days for anybody to raise issues for better suggestions.

• 31ed46b feature consuming: add autocommitting marked records
• c973268 feature fetches: add CollectRecords convenience function
• a478251 bugfix source: advance offsets even if we return no records
• 307c22e minor bugfix client retriable req: fix err bug
• fcaaf3f breaking kmsg: update per protocol changes
• 262afb4 bugfix offset commit: use -1 for RetentionTimeMillis
• c6df11d consumer: commit all dirty offsets when entering poll
• e185676 (minor) breaking change: AllowedConcurrentFetches => MaxConcurrentFetches
• d5e80b3 bump min go version to go1.15

v0.10.2

This release contains everything currently outstanding for a v1.0.0 release. Primarily, this release addresses #57, meaning that by default, auto committing no longer has the potential to lose records during crashes. It is now highly recommended to have a manual CommitUncommittedOffsets before shutting down if autocommitting, just to prevent any unnecessary duplicate messages.

The aim is to let this release bake for a day / a few days / a week so that if anybody tries it out, I can receive any bug reports.

• 31754a9 feature-ish compression: switch snappy to @klauspost's s2
• 28bba43 autocommitting: only commit previously polled fetches
• 4fb0de2 isRetriableBrokerErr: opt in net.ErrClosed, restructure
• 0d01f74 feature add RoundRobinPartitioner
• 5be804d LeastBackupPartitioner: fix, speedup
• 733848b bugfix CommitRecords: commit next offset to move forward
• 4c20135 bugfix/simplification sink: simplify decInflight for batches in req

v0.10.1

This fix contains an important bugfix for some behavior introduced in v0.9.1, as well as extra debug logging messages, and a few other general improvements. Some more errors are now retriable in more cases, and the client can now tolerate some input seeds being invalid when others are not invalid.

It is highly recommended that any use of v0.9.1 switch to v0.10.1. If on v0.9.1 and a produced batch has a retriable error, and then some cluster maintenance causes the partition to move to a different broker, the client will be unable to continue producing to the partition.

• 029f5e3 bugfix sink: fix decInflight double decrement bug
• 2cf62e2 sink: properly debug log the number of records written
• 370c18e and caadb8b feature: add LeastBackupPartitioner
• 0fee54c and 589c5e5 add errUnknownBroker and io.EOF to be retriable errors in sink; add errUnknownBroker to be skippable in the client
• ec0c992 client improvement: retry more when input brokers are invalid

v0.10.0

#62 now tracks the v1.0.0 stabilization status. This release contains everything but addressing #57, which I would like to address before stabilizing.

After using this client some more in a different program, I've run into some things that are better to break now. Particularly, a few options are awkward. The goal is for this release to make these options less awkward.

Three options have been renamed in this release, the fixes are very simple (and ideally, if you used RetryTimeout, you may find the new RetryTimeout even simpler).

• c1d62a7 feature config: add DialTLSConfig option
• 4e5eca8 breaking: rename ProduceRetries to RecordRetries
• 12808d5 breaking: rename RetryBackoff to RetryBackoffFn
• 8199f5b breaking: split RetryTimeout function

v0.9.1

v0.9.0 is to be stabilized, but I would like to address #57 first, which may slightly change how autocommitting works. This intermediate release pulls in some decent fixes.

• fd889cc all: work around brokers that have inconsistent request versions
• f591593 broker: permanently store the initial ApiVersions response
• 8da4eaa and 37ecd21 feature client: enable ipv6 support in seed brokers (thanks @vtolstov and @SteadBytes!)
• aecaf27 bugfix client: force a coordinator refresh if the coordinator is unknown
• f29fb7f bugfix sink: fix out-of-order response handling across partition rebalances
• 4fadcde rare bugfix consuming: fix logic race, simplify some logic

v0.9.0

This is a v1.0 release candidate. The only breaking change in this release is that the kmsg package is now a dedicated module.

Why have a module for kmsg?

The kmsg package is almost entirely autogenerated from the Kafka protocol. Unfortunately, the Kafka protocol is mostly designed for an object oriented language (i.e., Java), so some changes to the Kafka protocol that are non-breaking are breaking in the kmsg package. In particular, the Kafka changes a non-nullable field to a nullable field, the kmsg package must change from a non-pointer to a pointer. This is a breaking change. Even more rarely, sometimes Kafka changes a field's type by renaming its old version to "SomethingOld" and having a new version take the place of "Something". I would prefer the kmsg avoid "SomethingNew" to avoid deprecating the old field, so I also choose to rename fields.

One option is to have absolutely everything be a pointer in the kmsg package, but this would create a lot of garbage and make using the API even worse. As well, I could just add newly named fields, but this makes things worse as time goes on, because the newer fields would be the ones with the worse names.

In Go, if kmsg were stabilized, any protocol change would need to be a major version bump. We cannot get away with minor bumps and a big doc comment saying "deal with it", because we run into a transitive dependency issue: if user A uses franz-go at v1.1.0, and they also use a library that uses franz-go at v1.0.0, and there is an incompatible kmsg change, then the user's compilation breaks.

So, we choose to have a dedicated module for kmsg which is unversioned. This avoids some transitive dependency issues.

If you use the kmsg package directly, the only update you should need to do is:

go get -u github.com/twmb/franz-go/pkg/kmsg@latest

Other potentially notable changes

• f82e5c6 consumer: document that a nil / closed context is supported for polling
• 8770662 very minor bugfix for producing: only opt in to more than 1req if idempotent
• 5c0a2c7 bench: add -prometheus flag

v0.8.7

This release contains commits for upcoming Kafka protocol changes, new features to gain insight into buffered records (and intercept & modify them before being produced or consumed), a few minor other changes, and one minor breaking change.

The minor breaking change should not affect anybody due to its rather niche use when better methods exist, but if it does, the fix is to delete the Partitions field that was removed (the field is now embedded).

This field was removed just for ease of use purposes: there was no reason to have a separate named field in FetchTopicPartition for the Partition, instead, we can just embed FetchPartition to make usage of the type much simpler. Dropping this field basically makes this type much more appealing to use.

I may be releasing v0.9.0 shortly, with plans to potentially split the kmsg package into a dedicated module. More details on that if this happens.

Breaking change

• ffc94ea minor breaking change: embed FetchPartition in FetchTopicPartition rather than have a named Partition field

Features

• 1bb70a5 kprom: clarify seed ids, add two new metrics
• 916fc10 client: add four new hooks to provide buffer/unbuffer interceptors
• 1e74109 hooks: add HookNewClient
• 3256518 client: add Buffered{Produce,Fetch}Records methods
• ebf2f07 support KIP-516 for Fetch (topic IDs in fetch requests)
• e5e37fc and 3a3cc06 support KIP-709: batched OffsetFetchRequest in a forward-compatible way (and minor group sharded request redux)
• eaf9ebe kprom: use Registerer and Gatherer interface instead of concrete registry type.
• 10e3f44 and 4fdc7e0 support KIP-699 (batch FindCoordinator requests)

Minor other changes

• d9b4fbe consumer group: add "group" to all log messages
• f70db15 broker: use ErrClientClosed more properly for internal requests that use the client context
• 8f1e732 producer: use ErrClientClosed properly if waiting to produce when the client is closed
• ee918d9 sink: drop the drain loop sleep from 5ms to 50microsec
• e48c03c client: log "seed #" rather than a large negative for seed brokers

v0.8.6

• 7ec0a45 bugfix consumer group: bugfix regex consuming (from v0.8.0+)
• 91fe77b bench: faster record value generation, add -static-record flag
• f95859e generated code: always return typed value if present
• db5fca5 support KIP-734
• ae7182b group balancing: address KAFKA-12898

This small tag fixes a bug in group consuming via regex, adds a new -static-record flag to the benchmark example, and has a few other very minor changes (see commits).

Also, thank you @Neal for fixing some typos and eliminating a useless goroutine in the benchmarks!

v0.8.5

• 2732fb8 bugfix consumer: bugfix consuming of specific partitions if no topics are specified

If ConsumePartitions was used without ConsumeTopics, the consumer would not start. This was missed in the conversion of starting the consumer after initializing a client to initializing the consumer with the client.

v0.8.4

• e0346a2 very minor bugfix consumer group: set defaultCommitCallback
• 5047b31 and 05a6b8a bench: add -linger, -disable-idempotency, -log-level, -compression, -batch-max-bytes options

This is a small release containing a very minor bugfix and more flags on the benchmark program. The bugfix basically re-adds a missing commit callback if you are not specifying your own, and the default commit callback just logs errors. So in short, this release ensures you see errors if there are any and you are using the default commit callback.

v0.8.3

• 053911b plugins: fix module declarations

This is a patch release on the prior commit to fix the path declarations in the new plugin modules.

v0.8.2

• 65a0ed1 add pluggable kgmetrics, kprom, kzap packages & examples

This release immediately follows the prior release so that the plugin packages can refer to v0.8.1, which contains the (hopefully) final API breakages. This allows Go's version resolution to ensure users of these plugins use the latest franz-go package.

These new plugins should make it very easy to integrate prometheus or go-metrics or zap with kgo.

v0.8.1

This release contains a few features, one minor bugfix, two minor breaking API changes, and a few minor behavior changes.

This release will immediately be followed with a v0.8.2 release that contains new examples using our new hooks added in this release.

Breakage

One of the breaking API changes is followup from the prior release: all broker-specific hooks were meant to be renamed to OnBrokerXyz, but I missed OnThrottle. This is a rather niche hook so ideally this does not break many/any users.

The other breaking API change is to make an API consistent: we have Produce and ProduceSync, and now we have CommitRecords and CommitUncommittedOffsets in addition to the original CommitOffsets, so BlockingCommitOffsets should be renamed to CommitOffsetsSync. This has the added benefit that now all committing functions will be next to each other in the documentation. One benefit with breaking this API is that it may help notify users of the much more easily used CommitUncommittedOffsets.

Features

• Two new partitioners have been added, one of which allows you to set the Partition field on a record before producing and have the client use that field for partitioning.

• Two new hooks have been added that allow tracking some metrics per-batch while producing and consuming. More per-batch metrics can be added to the hooks later if necessary, because the hooks take a struct that can be expanded upon.

• The client now returns an injected ErrClientClosed fetch partition when polling if the client has been closed, and Fetches now contains a helper IsClientClosed function. This can be used to break out of a poll loop on shutdown.

Behavior changes

• The client will no longer add empty fetches to be polled. If fetch sessions are disabled, or in certain other cases, Kafka replies to a fetch requests with the requested topics and partitions, but no records. The client would process these partitions and add them to be polled. Now, the client will avoid adding empty fetches (unless they contain an error), meaning polling should always have fetches that contain either records or an error.

• When using sharded requests, the client no longer issues split pieces of the requests to partitions that are currently erroring. Previously, if a request needed to go to the partition leader, but the leader was offline, the client would choose a random broker to send the request to. The request was expected to fail, but the failure error would be retriable, at which point we would reload metadata and hope the initial partition leader error would be resolved. We now just avoid this try-and-fail-and-hope loop, instead erroring the split piece immediately.

Examples

This contains one more example, examples/group_consuming, which demonstrates how to consume as a group and commit in three different ways, and describes the downsides of autocommitting.

Changes

• fa1fd35 feature consuming: add HookFetchBatchRead
• 9810427 feature producing: add HookProduceBatchWritten
• 20e5912 breaking api hook: rename OnThrottle => OnBrokerThrottle
• a1d7506 examples: add group consumer example, with three different commit styles
• 058f692 behavior change, consuming: only add fetch if it has records or errors
• d9649df feature fetches: add IsClientClosed helper
• bc0add3 consumer: inject ErrClientClosing when polling if the client is closed
• f50b320 client: make public ErrClientClosed
• 8b7b43e behavior change, client: avoid issuing requests to shards that we know are erroring
• 96cb1c2 bugfix fix ACLResourcePatternType: add ANY
• 8cf3e5a breaking api rename BlockingCommitOffsets to CommitOffsetsSync
• 2092b4c and 922f4b8 feature add CommitRecords and CommitUncommittedOffsets
• 6808a55 feature add BasicConsistentPartitioner / ManualPartitioner

v0.8.0

This is a major breaking release. This release is intended to be a release candidate for a v1.0.0 tag; thus, I wanted to nail down all API breakage now to help prevent future breakage and to ensure a path towards 1.0 stabilization. I do not expect major API changes after this tag, and I intend to release v1.0.0 within a month of this tag.

Why the breakage?

It never felt "right" that to consume, you needed to first create a client, and then assign something to consume. One large reason that AssignXyz existed was so that you could reassign what was being consumed at runtime. In fact, you could consume from a group, then leave and switch to direct partition consuming, and then switch back to consuming from a different group. This flexibility was unnecessary, and assigning after the client was initialized was awkward. Worse, allowing these reassignments necessitated extreme care to not have race conditions or deadlocks. This was the source of many bugs in the past, and while they have since been ironed out, we may as well just remove them as a possibility while on the path towards v1.0.

Because we have this one major breakage already, I decided it was a good time to clean up the other not-so-great aspects of the code.

• All current hooks have been renamed, because OnE2E being dedicated to brokers does not leave room for a different E2E hook in the future that is not specific to brokers. Instead, if we namespace the current broker hooks, we can namespace future hooks as well, and nothing will look weird. More beneficially, in user code, the hook will be more self describing.

• One now redundant option has been removed (BrokerConnDeadRetries), and one useless option has been removed (DisableClientID).

Moving consumer options to the client required changing the names of some consumer options, merging some duplicated group / direct options, adding *Client as an argument to some callbacks, and cleaning up some consume APIs.

From there on, the breakages get more minor: AutoTopicCreation now is AllowAutoTopicCreation, and ProduceTopic is now DefaultProduceTopic.

Upgrade considerations

Due to the number of breaking changes, upgrading may look more difficult than it actually is. I've updated every example in this repo and all code usage in my corresponding kcl repo, these updates were completed relatively quickly.

tl;dr of upgrading

The simpler fixes:

• Change AutoTopicCreate to AllowAutoTopicCreate
• Change ProduceTopic to DefaultProduceTopic
• Remove BrokerConnDeadRetries and DisableClientID if you used them (unlikely)
• Add Broker in any hook (OnConnect => OnBrokerConnect, etc)

If directly consuming, perform the following changes to options and move the options to NewClient:

• Drop the offset argument from ConsumeTopics
• Move ConsumePartitions
• Change ConsumeTopicsRegex to ConsumeRegex
• Delete AssignPartitions

If group consuming, perform the following changes to options and move the options to NewClient:

• Add ConsumerGroup with the group argument you used in AssignGroup
• Change GroupTopics to ConsumeTopics
• Add a *Client argument to any of OnAssigned, OnRevoked, OnLost, and CommitCallback

If using a group transaction session, perform the above group changes, and use NewGroupTransactSession, rather than NewClient.

Changes

• 6a048db breaking API hooks: namespace all hooks with Broker
• 8498383 breaking API client: large breaking change for consuming APIs
• 45004f8 breaking API config: rename ProduceTopic to DefaultProduceTopic, doc changes
• aa849a1 breaking API options: prefix AutoTopicCreation with Allow
• be6adf5 breaking API client: remove DisableClientID option
• 68b1a04 breaking API client: remove BrokerConnDeadRetries option; drop retries to 20
• 88e131d bugfix kerberos: fix off-by-one in asn1LengthBytes (but it appears this is still not fully working)
• 20e0f66 feature Fetches: add EachError, clarifying documentation
• 085ad30 metadata: limit retries, bump produce load errors on failure
• b26489f config: change default non-produce retries from unlimited to 30 (later commit just above changes down to 20)

v0.7.9

• 5231902 bugfix patch on prior commit

If I could yank tags, I would.

v0.7.8

• b7cb533 bugfix allow any *os.SyscallError to be retriable

This should be the last v0.7 release. This is a small bugfix to allow much more retrying of failing requests, particularly around failed dials, which is much more resilient to restarting brokers.

v0.7.7

• afa1209 txn: detect a fatal txnal client when beginning transactions
• 5576dce benchmarks: add comparisons to confluent-kafka-go & sarama
• d848174 examples: add benchmarking example
• fec2a18 client: fix request buffer pool, add promisedNumberedRecord pool
• a0d712e transactions: small wording changes in docs
• bad47ba and a9691bd feature hooks: add HookBrokerE2E

This is a small release with one useful new hook, a few minor updates / internal fixes, and no bug fixes.

This now properly pools request buffers, which will reduce garbage when producing, and re-adds pooling slices that records are appended to before flushing. This latter pool is less important, but can help.

This now adds one more chance to recover a transactional client, which also gives the user a chance to things are fatally failed when beginning transactions.

Finally, this adds a benchmarking example and comparisons to sarama / confluent-kafka-go. To say the least, the numbers are favorable.

This is likely the last release of the v0.7 series, the next change will be a few breaking API changes that should hopefully simplify initializing a consumer.

v0.7.6

This is a small release that adds defaults for any kmsg.Request that has a TimeoutMillis field that previously did not have a default.

This also changes how the TimeoutMillis field is specified for generating, and now all documentation around it is consistent.

Lastly, any field that has a default now has that default documented.

v0.7.5

This commit adds support for session tokens and user agents in AWS_MSK_IAM, as well as adds an example for how to use AWS_MSK_IAM.

v0.7.4

• 467e739 FirstErrPromise: change semantics

This is a small release to change the semantics of FirstErrPromise: now, it uses a sync.WaitGroup on every Promise and will wait until all records have been published / aborted before returning from Err. This also adds an AbortingFirstErrPromise that automatically aborts all records if any promise finishes with an error.

v0.7.3

• 30c4ba3 feature sasl: add support for AWS_MSK_IAM

This is a small release dedicated to adding support for AWS_MSK_IAM sasl.

v0.7.2

• 522c9e2 bugfix consumer group: use JoinGroupResponse.Protocol, not SyncGroupResponse.Protocol

This is a small bugfix release; the Protocol field in SyncGroupResponse was added in 2.5.0, and my integration tests did not catch this because I usually test against the latest releases. All JoinGroupResponse versions have the protocol that was chosen, so we use that field.

v0.7.1

• 98f74d1 README: note that we actually do support KIP-533
• 528f007 and ef9a16a and d0cc729 bugfix client: avoid caching invalid coordinators; allow retries

This is a small bugfix release: previously, if FindCoordinator returned a node ID of -1, we would permanently cache that. -1 is returned when the load has an error, which we were not checking, but even still, we should not cache the response if we do not know of the broker.

Now, we will only cache successful loads.

(Also, I noticed that I do have an existing configuration knob for the retry timeout, so that is now "Supported" in the KIP section, making all KIPs supported).

v0.7.0

This is a big release, and it warrants finally switching to 0.7.0. There are a few small breaking changes in this release, a lot of new features, a good few bug fixes, and some other general changes. The documentation has been overhauled, and there now exists an example of hooking in to prometheus metrics as well as an example for EOS.

Most of the new features are quality of life improvements; I recommend taking a look at them to see where they might simplify your code.

Upgrade considerations

Besides the two breaking changes just below, one bug fix may affect how you if you are using a group consumer with autocommitting. If autocommitting, the consumer should always have been issuing a blocking commit when leaving the group to commit the final consumed records. A bug existed such that this commit would never actually be issued. That bug has been fixed, so now, if you rely on autocommitting, the client closing may take a bit longer due to the blocking commit.

Breaking changes

There are two breaking changes in this release, one of which likely will go unnoticed. First, to allow all hooks to display next to each other in godoc, the interfaces have had their trailing "Hook" moved to a leading "Hook". Second and definitely noticeable, record producing no longer returns an error. The original error return was not really that intuitive and could lead to bugs if not understood entirely, so it is much simpler to just always call the promise.

• 215f76f small breaking API: prefix hook interfaces with "Hook"
• c045366 producer: drop error return from Produce (breaking API change)

Features

• c83d5ba generate: support parsing and encoding unknown tags
• 6a9eb0b kmsg: add Tags opaque type; ReadTags helper
• 9de3959 add support for KIP-568 (force rebalance)
• d38ac84 add HookGroupManageError
• 0bfa547 consumer group: add CommitCallback option
• 231d0e4 fetches: add EachRecord
• aea185e add FirstErrPromise
• 780d168 Record: add helper constructors; allocation avoiders w/ unsafe
• 55be413 producer feature: allow a default Topic to produce to
• e05002b and 1b69836 consumer group: export APIs allow custom balancers
• 6db1c39 Fetches: add EachTopic helper
• b983d63, 7c9f591, 3ad8fc7, and 3ad8fc7 producer: add ProduceSync

Bug fixes

• 45cb9df consumer: fix SetOffsets bug
• 46cfcb7 group: fix blocking commit on leave; potential deadlock
• 1aaa1ef consumer: fix data race in handleListOrEpochResults
• d1341ae sticky: fix extreme edge case for complex balancing
• 9ada82d sink: create producerID BEFORE produce request (partial revert of dc44d10b)
• 5475f6b sink: bugfix firstTimestamp
• 2c473c4 client: add OffsetDeleteRequest to handleCoordinatorReq
• bf5b74c and 3ad8fc7 broker: avoid reaping produce cxn on no reads when acks == 0
• 43a0009 sink w/ no acks: debug log needs to be before finishBatch
• 8cf9eb9 sink: bugfix panic on acks=0

General

• 939cba2 txns: make even safer (& drop default txn timeout to 40s)
• faaecd2 implement KIP-735 (bump session timeout to 45s)
• 3a95ec8 GroupTxnSession.End: document no error is worth retrying
• c5a47ea GroupTransactSession.End: retry with abort on OperationNotAttempted
• 6398677 EndTxn: avoid creating a producer ID if nothing was produced
• c7c08fb txnal producer: work around KAFKA-12671, take 2
• 9585e1d FetchesRecordIter: avoid mutating input fetches

v0.6.14

• dc44d10 sink: call producerID after creating the produce request
• ce113d5 bugfix producer: fix potential lingering recBuf issue
• 19d57dc bugfix metadata: do not nil cursors/records pointers ever
• e324b56 producing: evaluate whether a batch should fail before and after

This is a small bugfix release for v0.6.13, which would panic if a user was producing to and consuming from the same topic within a single client.

At the same time, there was a highly-unlikely-to-be-experienced bug where orphaned recBuf pointers could linger in a sink through a certain sequence of events (see the producer bugfix commit for more details).

This also now avoids initializing a producer ID when consuming only. For code terseness during the producer redux, I moved the createReq portion in sink to below the producerID call. We actually call createReq when there are no records ever produced: a metadata update adding a recBuf to a sink triggers a drain, which then evaluates the recBuf and sees there is nothing to produce. This triggered drain was initializing a producer ID unnecessesarily. We now create the request and see if there is anything to flush before initializing the producer ID, and we now document the reason for having producerID after createReq so that I do not switch the order in the future again.

Lastly, as a feature enhancement, this unifies the logic that fails buffered records before producing or after producing. The context can now be used to cancel records after producing, and record timeouts / retries can be evaluated before producing. The order of evaluation is first the context, then the record timeout, and lastly the number of tries.

v0.6.13

• 6ae76d0: feature producer: allow using the passed in context to cancel records
• 2b9b8ca: bugfix sink: reset needSeqReset
• 314de8e: feature producer: allow records to fail when idempotency is enabled
• bf956f4: feature producer: delete knowledge of a topic if we never load it
• 83ecd8a: bugfix producer unknown wait: retry on retriable errors
• a3c2a5c: consumer: backoff when list offsets or load epoch has any err (avoid spinloop)
• 9c27589: zstd compression: add more options (switch to minimal memory usage)
• 0554ad5: producer: retry logic changes

This release focuses on restructing some code to allow deleting topics from the client and, most importantly, to allow records to fail even with idempotency.

For deleting records, this is a minimal gain that will really only benefit a user reassigning consuming topics, or for producers to a topic that does not exist. Still, nifty, and for an EOS user, produce and consume topics will no longer be next to each other (which may make scanning partitions to produce or consume quicker).

For allowing records to have limited retries / be canceled with a context, this is an important feature that gives users more control of aborting the work they tried. As noted in the config docs, we cannot always safely abort records, but for the most part, we can. The only real unsafe time is when we have written a produce request but have not received a response. If we ever get a response for the first batch in a record buffer (or if we do not write the batch ever), then we can safely fail the records. We do not need to worry about the other concurrent requests because if the first batch errors, the others will error and we know we can fail records based off the first's status, and if the first batch does not error, we will just finish the records (and not error them).

v0.6.12

This is a small release corresponding with Kafka's 2.8.0 release. A few small things were fixed when trying out kcl misc probe-versions with the new code, and with that, we are able to determine exactly where to cut 2.8.0 from tip in the kversion package.

Lastly, this also converts topic IDs that are introduced in this release from [2]uint64 to [16]byte. A raw blob of bytes is easier to reason about and affords us avoiding worrying about endianness.

v0.6.11

• 46138f7: feature client: add ConnIdleTimeout option && connection reaping (further fix to this in later commit)
• 26c1ea2: generate: return "Unknown" for unknown NameForKey
• 557e15f: module change update module deps; bump lz4 to v4. This dep update will require go-getting the new v4 module.
• 10b743e: producer: work around KAFKA-12671
• 89bee85: bugfix consumer: fix potential slowReloads problem
• 111f922: consumer: avoid bubbling up retriable broker errors
• fea3195: bugfix client: fix fetchBrokerMetadata
• 6b64728: breaking API: error redux -- this makes private many named errors; realistically this is a minor breaking change
• b2a0578: sink: allow concurrent produces (this was lost in a prior release; we now again allow 5 concurrent produce requests per broker!)
• ebc8ee2: bugfix / improvements producer: guts overhaul, fixing sequence number issues, and allowing aborting records when aborting transactions
• 39caca6: Poll{Records,Fetches}: quit if client is closed
• 56b8308: bugfix client: fix loadCoordinators
• d4fe91d: bugfix source: more properly ignore truncated partitions
• 71c6109: bugfix consumer group: map needs to be one block lower
• 009e1ba: consumer: retry reloading offsets on non-retriable errors
• 6318b15: bugfix group consumer: revoke all on LeaveGroup, properly blocking commit
• b876c09: bugfix kversion: KIP-392 landed in Kafka 2.3, not 2.2
• 1c5af12: kversion: support guessing with skipped keys, guessing raft

This is an important release with multiple bug fixes. All important commits are noted above; less important ones are elided.

The producer code has been overhauled to more accurately manage sequence numbers. Particularly, we cannot just reset sequence numbers whenever. A sequence number reset is a really big deal, and so we should avoid it at all costs unless absolutely necessary.

By more accurately tracking sequence numbers, we are able to abort buffered records when aborting a transact session. The simple approach we take here is to reset the producer ID after the abort is completed.

The most major consumer bug was one that incorrectly tracked uncommitted offsets when multiple topics were consumed in a single group member. The other bugs would be infrequently hit through some more niche edge cases / timing issues.

The lz4 module was updated, which will require a go mod edit. This was done because major-version-bumping is pretty undiscoverable with mod updates, and it turns out I had always used v1 instead of v4.

Sometime in the past, a broker/producer bugfix accidentally lost the ability to send 5 concurrent produce request at once. That ability is readded in this release, but this can occasionally trigger a subtle problem within Kafka while transactionally producing. For more details, see KAFKA-12671. The client attempts to work around this problem by sleeping for 1s if it detects the problem has a potential of happening when aborting buffered records. Realistically, this problem should not happen, but the one way to easily detect it is to look for a stuck LastStableOffset.

A ConnIdleTimeout option was added that allows for reaping idle connections. The logic takes a relatively easy approach, meaning idle connections may take up to 2x the idle timeout to be noticed, but that should not be problematic. This will help prevent the problem of Kafka closing connections and the client only noticing when it goes to eventually write on the connection again. This will also help avoid sockets in the kernel being stuck in CLOSE_WAIT.

Finally, after being inspired from KAFKA-12675, I have significantly optimized the sticky assignor, as well as added other improvements for the cooperative adjusting of group balancer plans.

v0.6.10

• 04f8e12: update debug logging (broker and consumer group)
• 62e2e24: add definitions & code for control record keys and values
• e168855: bugfix sticky: fix and drastically simplify isComplex detection
• bd5d5ad: bugfix consumer: properly shut down manageFetchConcurrency
• a670bc7: group balancer: debug => info logging; handle join better
• d74bbc3: bugfix group: avoid concurrently setting err; use better log message
• ca32e19: feature consumer: add PollRecords to poll a limited number of records
• 2ce2def: txn: change what we set offsets to on revoke / error
• 582335d: txn: add PollFetches and Produce to GroupTransactSession
• c8cd120: txn: document that canceling contexts is not recommended
• bef2311: enforce KIP-98 idempotency config rules: acks=all, retries > 0
• 2dc7d3f: bugfix client.EndTransaction: if offsets were added to transaction, ensure we commit
• 938651e: bugfix consumer & consumer group: small redux, bug fixes
• b531098: feature add support for ListTransactions, minor DescribeTransactions change
• 3e6bcc3: feature client: add option to disable idempotent writes
• 5f50891: feature: kgo.Fetches: add EachPartition callback iterator
• 05de8e6: bugfix use proper keyvals for join group error
• 8178f2c: group assigning: add debug logs for balancing plans
• e038916: bugfix range balancer: use correct members for div/rem
• e806126: bugfix (minor) broker: shift sizeBuf 1 left by 8 for guessing tls version
• cd5e7fe: client: rewrite *kmsg.ProduceRequest's Acks, TimeoutMillis
• 8fab998: kgo: use a discard goroutine when produce acks is 0

This is an important release that fixes various bugs in the consumer code and adds a few nice-to-have features. Particularly, this includes a minor redux of the consumer group code that audited for correctness, and includes a few transactional consumer fixes.

There is a known problem in sequence numbers in the producer code that will be hit if any consumer resets its sequence numbers. This happens if a consumer hits a produce timeout or hits the retry limit, and may happen if AbortBufferedRecords is called. A fix for this is being worked on now and will be in the next release.

Most commits since v0.6.9 are noted above, minus a few that are left out for being very minor documentation updates or something similar.

v0.6.9

• 0ca274c: bugfix consumer group: fix race where we did not wait for a revoke to finish if the group closed
• 0cdc2b6: bugfix consumer: process FetchResponse's RecordBatches correctly (versions after v0.11.0 can use message sets)
• bcb330b: kerr: add TypedErrorForCode and four new errors
• 31a9bbc: bugfix (that is not hit by general consumers): FetchResponse's DivergingEpoch.EndOffset is an int64, not int32

This release fixes some problems with consuming. As it turns out, message sets, which are unused after v0.11.0, are indeed returned with higher FetchResponse versions. Thus, we cannot rely on the FetchResponse version alone to decide whether to decode as a message set or a record batch, instead we must check the magic field.

The DivergingEpoch.EndOffset bug likely would not be noticed by general consumers, as this is a field set by leaders to followers and is not useful to nor set for clients. As well, it's only used for the not-yet-finalized raft work.

I noticed a race while looping through integration tests in -race mode, this was an easy fix. Practically, the race can only be encountered when leaving a group if your revoke is slow and the timing races exactly with the manage loop also revoking. This would mean your onRevoke could be called twice. Now, that will not happen. This bug itself is basically a reminder to go through and audit the consumer group code, one of the last chunks of code I intend to potentially redux internally.

v0.6.8

• 8a42602: bugfix kversion: avoid panic on a key with value of max int16 (32767)

This is a small bugfix release; Confluent replies with odd keys sometimes, turns out this time it was max int16. That showed that the parentheses was in the wrong place for SetMaxKeyVersions.

This also has one more commit that change the String output a little bit to use "Unknown" instead of an empty string on unknown keys.

v0.6.7

• 2bea568: bugfix producer: fix producing with NoAck
• d1ecc7b: On invalidly broker large reads, guess if the problem is a tls alert on a plaintext connection

This is a small bugfix release to fix producing with no acks. As it turns out, Kafka truly sends no response when producing with no acks. Previously, we would produce, then hang until the read timeout, and then think the entire request failed. We would retry in perpetuity until the request retry limit hit, and then we would fail all records in a batch.

This fixes that by immediately finishing all promises for produce requests if we wrote successfully.

v0.6.6

• 21ddc56: kgo: sort RequestSharded by broker metadata before returning
• 4979b52: bugfix consumer: ensure we advance when consuming compacted topics

This is a small bugfix release to fix a stuck-consumer bug on compacted topics.

v0.6.5

• d5b9365: configuration: clamp max partition bytes to max bytes to work around faulty providers
• c7dbafb: bugfix consumer: kill the session if the response is less than version 7
• f57fc76: bugfix producer: handle ErrBrokerTooOld in doInitProducerID, allowing the producer to work for 0.10.0 through 0.11.0

This is a small release to ensure that we can make progress when producing to Kafka clusters v0.10.0 through v0.11.0 (as well as that we can consume from them if the consume has a partition error).

v0.6.4

• 802bf74: bugfix kgo: fix three races
• 1e5c11d: kgo: Favor non-seeds when selecting brokers for requests that go to a random broker
• 4509d41: kgo: Add AllowedConcurrentFetches option to allow bounding the maximum possible memory consumed by the client
• pr #22: Add transactional producer / consumer example (thanks @dcrodman!)
• 6a041a8: Add explicit Client.LeaveGroup method
• fe7d976: KIP-500 / KIP-631: add support for admin-level request DecommissionBroker
• ab66776: KIP-500 / KIP-631: add support for broker-only requests BrokerRegistration and BrokerHeartbeat
• 31b1df7: KIP-664: add support for DescribeProducers
• 368bb21: breaking kmsg protocol changes: add support for KIP-516 CreateTopics and DeleteTopics bumps
• b50282e: kerr: ReplicaNotAvailable is retriable; add UnknownTopicID
• c05572d: kmsg: change (Request|Response)ForKey to use proper NewPtr functions
• 360a4dc: client: actually use ConnTimeoutOverhead properly; bump base to 20s
• 0ff08da: Allow list offsets v0 to work (for Kafka v0.10.0 and before)
• 59c935c through c7caea1: fix fetch session bugs
• pr #4: Redesign readme (thanks @weeco!)

Of note, this fixes three races, fixes fetch session bugs and has small breaking protocol changes in kmsg.

For the three races, two of them are obvious in hindsight, but one makes no sense and may not belong in franz-go itself. The fix for the third is to remove a line that we do not need to do anyway.

For fetch sessions, sessions were not reset properly in the face of context cancelations or across consumer topic reassignments. It was possible for fetch sessions to get out of sync and never recover. This is fixed by resetting fetch sessions in all appropriate places.

For kmsg protocol changes, DeleteTopics changed Topics from a list of strings (topics to delete) to a list of structs where you could delete by topic or by topic uuid. The Java code coincidentally historically used TopicNames, so it did not need to break the protocol to add this new struct under the Topics name. For lack of confusion, we change Topics to TopicNames and introduce the struct under Topics.

v0.6.3

• db09137: Add support for new DescribeCluster API (KIP-700); followup commit (ab5bdd3) deprecates Include<*>AuthorizedOperations in the metadata request.
• 3866e0c: Set Record.Attrs properly before calling Produce callback hook.
• 05346db and 3d3787e: kgo: breaking change for kversions breaking change two commits ago (see two lines below)
• b921c14: doc fix: v0.10.0 changed produce from MessageSet v0 to MessageSet v1
• 33a8b26: Breaking pointerification change to kversions.Versions; introduce VersionGuess

Two small breaking changes related to kversions.Versions in this; switching to pointers now makes the struct future compatible; if it grows, we avoid the concern of passing around a large struct on the stack.

Contains one small fix related to KIP-360 w.r.t. the idempotent producer: when we encounter OutOfOrderSequenceNumber, we need to reset all partition's sequence numbers, not just the failing one. This is now done by resetting everything the next time the producer ID is loaded. The related Kafka ticket is KAFKA-12152.

v0.6.2

• 9761889: bump dependencies
• d07538d Allow clients to cancel requests with the passed context; fix potential hanging requests
• 303186a Add BrokerThrottleHook (thanks @akesle)
• 63d3a60 and previous commits: Use new & better kmsg.ThrottleResponse; this removes the usage of reflect to check for a ThrottleMillis field
• b68f112 kerr: add description to error string
• 7cef63c config: strengthen validation
• faac3cc producing: fail large messages more correctly (bugfix)
• bc1f2d1 and 2493ae7: kversion: switchup Versions API, finalize 2.7.0
• 991e7f3: Add support for KIP-630's new FetchSnapshot API
• de22e10: and 9805d36 and c1d9ff4: Add Uuid support and some definitions for KIP-516 (topic IDs)
• 539b06c: Completely rewrite the consumer.go & source.go logic and fix sink & source broker pointer issues
• 385cecb: Adds a warning hint if the connection dies on the first read without sasl
• 71cda7b: Bump another batch of requests to be flexible (per KAFKA-10729 / 85f94d50271)
• 9d1238b8e and 8a75a8091: Fix misleading doc comments on DescribeGroupsRequest and FindCoordinatorResponse
• 7f30228b8: Adds FetchMinBytes option
• 56ab90c72: Support EnvelopeRequest & DefaultPrincipalBuilder for KIP-590
• 37d6868fc: Add producer ID and epoch to the Record struct
• 9467a951d: Add explicit sharded requests and retriable broker specific requests (followup commit settles API naming; later commits fix small problems in initial implementation)
• b94b15549: Add kmsg constants for enums
• 7ac5aaff8: Add a MinVersions option
• 3b06d558b: Add a max broker read bytes option
• 4c5cf8422: Account for throttling in responses

The primary commit of this release is 539b06c, which completely rewrites the consumer.go and source.go files to be more easily understandable. This commit also fixes a bug related to the sink and source broker pointers; if the broker changed but kept the same node ID, the sink and source would not have their old pointers (to the old broker) updated.

There were some small breaking API changes in the kmsg package, most notably, the metadata request changed one field from a string to a *string due to Kafka switching the field from non-nullable to nullable. As specified in the kmsg docs, API compatibility is not guaranteed due to Kafka being able to switch things like this (and I favor small breakages like this rather than wrapping every type into a struct with a null field).

The kversion package has had its Versions type completely changed. The new format should be future compatible for new changes. The current change was required due to Kafka's ApiVersions having a gap in keys that it responds with in 2.7.0.

Config validation has been strengthened quite a bit.

Includes a few other minor, not too noteworthy changes.

v0.6.1

• 0ddc468b2: Workaround for two minor EventHubs issues.

This is a small release to patch around two minor EventHubs protocol serializing issues.

v0.6.0

• 0024a93a4: Fix bug introduced in pkg/kgo/source.go
• ee58bc706: Avoid noise when closing the client if we were not consuming
• 6e0b042e3: Pin the client by default to the latest stable API versions

This release also changes the name to franz-go. After sitting on frang for a week, ultimately I was missing the fact that the name related to Kafka. franz is an easy enough mental map, and then this brings back the -go suffix.

v0.5.0

• 9dc80fd29: Add hooks, which enable metrics to be layered in.
• a68d13bcb: Set SoftwareName & SoftwareVersion on ApiVersions request if missing
• 5fb0a3831: Fix SASL Authenticate
• 85243c5c5: Breaking API change for enums in ACL & config managing request / response types
• 4bc453bc2: Add NewPtr functions for generated structs in kmsg
• dcaf32daa: Generate RequestWith function for all requests in kmsg
• c27b41c3e: Add Requestor interface to kmsg package
• 2262f3a8f: Add New functions for generated structs in kmsg
• 7fc3a701e: Add UpdateFeatures for 2.7.0 (KIP-584)
• f09690186: Add shortcuts to get sasl.Mechanisms from sasl structs
• PR #12: Add clarifying wording on NewClient (thanks @weeco!)
• 9687df7ad: Breaking API change for kgo.Dialer
• aca99bcf1: New APIs for KIP-497 (alter isr)
• a5f66899f: New APIs for KIP-595 (raft)
• cd499f4ea: Fetch request changes for KIP-595 (raft)
• 7fd87da1c: Support defaults in generated code (and a few commits after adding defaults)
• 74c7f57e8: Support for KIP-584 (ApiVersions changes for min/max features)

Multiple generator changes were made to better handle tags, add support for enums, and parse many files in a definitions directory. Minor changes were made in kgo to use the new RequestWith function. More debug & warn log lines were added around opening a connection and initializing sasl.

This release also changed the name of the repo from "kafka-go" to "frang" to avoid potential trademark issues down the road.

v0.4.9

Typo fix for the prior release (in 2.7.0 APIs).

v0.4.8

• 2e235164d: Further prepare for KIP-588 (recover on txn timed out)
• 60de0dafb: Further audit for KIP-360 correctness (recoverable producer id)
• 2eb27c653: client.Request: shard DeleteRecords, {AlterReplica,Describe}LogDirs
• ebadfdae1: Add support for KIP-554 (SCRAM APIs)
• 4ea4c4297: Un-admin a lot of requests and fix OffsetDelete to be a group request

v0.4.7

• 598261505: Breaking API change in kmsg to add validating & erroring when reading records/messages

v0.4.6

• Introduces the CHANGELOG file
• ff1dc467e: Breaking API change in kmsg to support future non-breaking changes
• 4eb594044: Correctly copies over Version/ThrottleMillis when merging ListGroups