Use synchronous runtime for the main wasm execution lane#5095
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joshua-spacetime wants to merge 1 commit into
Open
Use synchronous runtime for the main wasm execution lane#5095joshua-spacetime wants to merge 1 commit into
joshua-spacetime wants to merge 1 commit into
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coolreader18
approved these changes
May 26, 2026
Comment on lines
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| fn wasm_main_worker_thread_name(database_identity: &spacetimedb_lib::Identity) -> String { | ||
| let hex = database_identity.to_hex(); | ||
| // We use the tail of the identity to avoid the common structured prefix. | ||
| let suffix = &hex.as_str()[hex.as_str().len() - THREAD_NAME_DATABASE_ID_SUFFIX_LEN..]; | ||
| format!("wasm-main-{suffix}") | ||
| } | ||
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| fn wasm_procedure_executor_thread_name(database_identity: &spacetimedb_lib::Identity) -> String { | ||
| let hex = database_identity.to_hex(); | ||
| // We use the tail of the identity to avoid the common structured prefix. | ||
| let suffix = &hex.as_str()[hex.as_str().len() - THREAD_NAME_DATABASE_ID_SUFFIX_LEN..]; | ||
| format!("wasm-{suffix}") | ||
| format!("wasm-proc-{suffix}") | ||
| } |
Contributor
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Max length of a linux thread name is 15, so this will only show wasm-proc-XXXXX, even though suffix is XXXXXXXX
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| if !self.supports_async { | ||
| let res = module_host_actor::ProcedureExecuteResult { | ||
| stats: zero_execution_stats(store), | ||
| call_result: Err(anyhow::anyhow!("procedures require an async Wasmtime instance")), | ||
| }; | ||
| return (res, None); | ||
| } |
Contributor
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Might it make sense for this to be an assert!()? I think this would be a programmer error, not something a user could run into.
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Description of Changes
Before this change, we used a single async-enabled wasm runtime for all requests, even though procedures are the only operation that can yield. Now each module gets two separate runtimes. We continue to use the same async runtime for procedures, but now reducers are executed against a synchronous wasm runtime, backed by a single OS-thread instead of a Tokio runtime.
The purpose of this change is to remove from the critical path the overhead associated with async calls that really aren't async at all.
API and ABI breaking changes
None
Expected complexity level and risk
2.5
Testing
Pure refactor. Relies on current test coverage. #5078 will ensure the performance is on par with V8.