Description
This is what can happen.
This is the potential race.
DrainDispatcher is started via serviceStart() . As a last step, this starts the actual dispatcher thread (eventHandlingThread.start() - and returns immediately - which means the thread may or may not have started up by the time start returns.
Event sequence:
UserThread: calls dispatcher.getEventHandler().handle()
This sets drained = false, and a context switch happens.
DispatcherThread: starts running
DispatcherThread drained = queue.isEmpty(); -> This sets drained to true, since Thread1 yielded before putting anything into the queue.
UserThread: actual.handle(event) - which puts the event in the queue for the dispatcher thread to process, and returns control.
UserThread: dispatcher.await() - Since drained is true, this returns immediately - even though there is a pending event to process.
Attachments
Attachments
Issue Links
- is related to
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YARN-5436 Race in AsyncDispatcher can cause random test failures in Tez (probably YARN also)
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- Resolved
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