[GitHub] [iotdb] choubenson commented on pull request #5693: [IOTDB-3018] Fix compation bugs on handling deleted target file and service shutdown deadlock

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choubenson commented on PR #5693:
URL: https://github.com/apache/iotdb/pull/5693#issuecomment-1111901493

   > > The third bug described in [IOTDB-3018](https://issues.apache.org/jira/browse/IOTDB-3018) my understanding after looking at the screenshot is that the main thread called stop, locked the CompactionTaskManager object with a synchronized block, while compaction thread needs to acquire the synchronized lock to submit sub compaction threads, which leads to the occurrence of deadlock. I don't know if it's the same bug as I understand, if so this bug has being fixed in [IOTDB-2966](https://github.com/apache/iotdb/pull/5610). It seems that CI is deadlocked?
   > 
   > The deadlock happens in:
   > 
   > 1. The main thread receives the kill signal and call the CompactionTaskManager.stop();
   > 2. CompactionTaskManager.stop() synchronizes itself, and call the taskExecutionPool.shutdown(), which will send Interrupt to all the running threads. And it calls the `waitTermination()`, which loops infinitely until the pool is terminated.
   >    **Note that now the lock is being held by the main thread until all the tasks are finished.**
   > 3. Now supposing we have 1 compaction task running, it breaks by the InterruptException, and calls ` CompactionTaskManager.getInstance().removeRunningTaskFuture(this);` in the finally block.
   > 4. `removeRunningTaskFuture` also wants to acquire the lock of CompactionTaskManager, however it's already locked in 1. Here a dead lock happens.
   > 
   > So I think this is another deadlock scenario other than the test case.
   
   Got it, thanks. :)


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