Flaky-test: ServerCnxTest.testCreateProducerTimeoutThenCreateSameNamedProducerShouldFail

[lhotari]

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Example failure

https://github.com/apache/pulsar/actions/runs/22088036654/job/63827409717#step:11:1050

Exception stacktrace

Error:  Tests run: 110, Failures: 1, Errors: 0, Skipped: 1, Time elapsed: 88.13 s <<< FAILURE! -- in org.apache.pulsar.broker.service.ServerCnxTest
  Error:  org.apache.pulsar.broker.service.ServerCnxTest.testCreateProducerTimeoutThenCreateSameNamedProducerShouldFail -- Time elapsed: 10.10 s <<< FAILURE!
  java.io.IOException: Failed to get response from socket within 10s
  	at org.apache.pulsar.broker.service.ServerCnxTest.getResponse(ServerCnxTest.java:2916)
  	at org.apache.pulsar.broker.service.ServerCnxTest.getResponse(ServerCnxTest.java:2892)
  	at org.apache.pulsar.broker.service.ServerCnxTest.testCreateProducerTimeoutThenCreateSameNamedProducerShouldFail(ServerCnxTest.java:2158)
  	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
  	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  	at java.base/java.lang.reflect.Method.invoke(Method.java:569)
  	at org.testng.internal.invokers.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:139)
  	at org.testng.internal.invokers.InvokeMethodRunnable.runOne(InvokeMethodRunnable.java:47)
  	at org.testng.internal.invokers.InvokeMethodRunnable.call(InvokeMethodRunnable.java:76)
  	at org.testng.internal.invokers.InvokeMethodRunnable.call(InvokeMethodRunnable.java:11)
  	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
  	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
  	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
  	at java.base/java.lang.Thread.run(Thread.java:840)

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• I'm willing to submit a PR!

[onceMisery]

Could you please assign this issue to me?

The root cause is test flakiness caused by using Netty’s EmbeddedChannel without reliably driving its event loop.

In ServerCnxTest.testCreateProducerTimeoutThenCreateSameNamedProducerShouldFail, the test sometimes waits for an outbound protocol response (and fails with java.io.IOException: Failed to get response from socket within 10s).
1
The response can be produced asynchronously (queued as a pending task on the channel’s embedded event loop). But the test’s “wait for response” logic effectively polls outboundMessages() and sleeps, and in the failing timing window it doesn’t execute the pending/scheduled tasks that would actually flush the response into the outbound queue—so the outbound queue stays empty until the 10s timeout.