Divij Vaidya created KAFKA-15205:
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Summary: ShutdownableThread
Key: KAFKA-15205
URL: https://issues.apache.org/jira/browse/KAFKA-15205
Project: Kafka
Issue Type: Bug
Affects Versions: 3.4.1, 3.3.2, 3.6.0, 3.5.1
Reporter: Divij Vaidya
Fix For: 3.6.0
In Shutdownable thread, during close, we call:
initiateShutdown() -> which may interrupt the thread if
isInterruptible is set to true during construction.
After that, we wait for proper shutdown using
awaitShutdown() which in-turn calls CountdownLatch#await(). On interruption,
which could be caused by initiateShutdown() earlier, await() throws an
InterruptedExeception. Hence, awaitShutdown() is going to exit by throwing an
interrupted exception.
The sequence to reproduce this will be as follows:
App-thread: Name of application thread which spawns and closes Shutdownable
thread
Shut-thread: Name of the shutdownable thread.
1. App-thread calls ShutThread.initiateShutdown()
2. ShutThread.interrupt() is called. It informs the VM to interrupt but the
actual interrupt will be async. initiateShutdown() from step 1 returns.
3. App-thread calls ShutThread.awaitShutdown()
4. App-thread waits on shutdownComplete.await() i.e. on CountdownLatch#await
5. VM decides to interrupt App-thread and there is a race condition now.
Race condition:
Condition 1: Shut-thread.doWork() gets interrupted exception, and decrements
the CountdownLatch
Condition 2: App-thread waiting on Shut-thread.shutdownComplete.await() throws
an interruptedException as per the contract
[https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CountDownLatch.html#await--]
*Solution*
In ShutDownableThread#awaitShutdown(), when calling await() we should catch
InterruptedException and eat it up (do nothing), if the thread has
isInterruptable set to true.
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