He-Pin opened a new pull request, #3149: URL: https://github.com/apache/pekko/pull/3149
### Motivation CAS retry loops in `AbstractDispatcher` and `Mailbox` spin without any CPU hint when contention causes `compareAndSet` to fail. JDK 9's `Thread.onSpinWait()` hints to the CPU that we're in a spin-wait loop, improving power efficiency and reducing context-switch latency. ### Modification - `AbstractDispatcher.scala`: Add `onSpinWait()` in shutdown schedule CAS retry loop body - `Mailbox.scala`: Convert `setAsScheduled()` and `setAsIdle()` from `@tailrec` recursive CAS loops to while loops with `onSpinWait()`, re-reading `currentStatus` on each retry ### Result Better CPU behavior under contention on the message dispatch hot path (`setAsScheduled` is called on every `registerForExecution`). The `onSpinWait` pattern is already established in the codebase (`AbstractNodeQueue`, `AbstractBoundedNodeQueue`, `AffinityPool`). ### Tests - `sbt "actor/compile"` — passed ### References Refs #3136 -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
