[GitHub] [druid] panhongan opened a new pull request #11292: fix future control bug for taskClient.pause

[GitBox <gi...@apache.org>]

panhongan opened a new pull request #11292:
URL: https://github.com/apache/druid/pull/11292


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   ### Description
   1. In our production system, a case like this:
   For `org.apache.druid.indexing.seekablestream.supervisor.SeekableStreamSupervisor#checkTaskDuration()`, if the following code timeout happens, then pausing tasks in taskClient were still running. 
   `List<Map<PartitionIdType, SequenceOffsetType>> results = Futures.successfulAsList(futures).get(futureTimeoutInSeconds, TimeUnit.SECONDS);`
   
   But finally the pausing task finished normally, the groupId will not be moved from `activelyReadingTaskGroups` to `pendingCompletionTaskGroups`, because the code block after above code will not be executed.
   
   Then next round `checkTaskDuration()` executed when the task has been PUBLISHING, "Can't pause exception" thrown.
   
   2. Furthermore, if the wild pausing task executed in thread pool for long time, the bad result is unknown. So if `checkTaskDuraion()` reaches to end whether normally or abnormally, all pausing tasks should be finished.
   
   3. Solution
   1) In `SeekableStreamIndexTaskClient`, add some code to manage the pausing tasks, can submit and stop task.
   2) In `SeekableStreamSupervisor`, If `checkTaskDuraion()` reaches to end, `taskClient` can ensure that all the pausing tasks are finished.
   
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   #### Fixed the bug ...
   1. SeeableStreamIndexTaskClient
   [Class organization and design]
   1) Add a class `PauseCallable`, implements from Callable,  to wrap the pausing task feature and provide `stop()` to trigger the pausing task can be finished.
   2) Move `pause()` from `class SeeableStreamIndexTaskClient` to `class PauseCallable`
   
   2. SeeableStreamIndexSupervisor
   [Method organization and design]
   1) Add a single method `moveGroupFromReadingToPending()` for each finished pausing task.
   2) Add finally block in `checkTaskDuration()`, that ensures taskClient can control all the running tasks.
   
   #### Renamed the class ...
   [No]
   
   #### Added a forbidden-apis entry ...
   [No]
   
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   <hr>
   
   ##### Key changed/added classes in this PR
    * `org.apache.druid.indexing.seekablestream.supervisor.SeekableStreamSupervisor` (changed)
    * `org.apache.druid.indexing.seekablestream.SeekableStreamIndexTaskClient` (changed)
   
   
   <hr>
   
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   This PR has:
   - [ x] been self-reviewed.
      - [x ] using the [concurrency checklist](https://github.com/apache/druid/blob/master/dev/code-review/concurrency.md) (Remove this item if the PR doesn't have any relation to concurrency.)
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   - [x] added integration tests.
   - [x] been tested in a test Druid cluster.
   


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[GitHub] [druid] panhongan closed pull request #11292: fix future control bug for taskClient.pause

[GitBox <gi...@apache.org>]

panhongan closed pull request #11292:
URL: https://github.com/apache/druid/pull/11292


   


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