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https://issues.apache.org/jira/browse/DRILL-6125?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16374057#comment-16374057
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ASF GitHub Bot commented on DRILL-6125:
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Github user ilooner commented on the issue:

    https://github.com/apache/drill/pull/1105
  
    @priteshm @arina-ielchiieva I should have updated this PR earlier this 
week, here is my update. After reflecting on Arina's comments and reading some 
more docs about how java implements volatile and synchronization, I think this 
solution might not fix the original race condition. I need to to more reading 
to get a better understanding. Additionally I realized there is another race 
condition where two threads are simultaneously calling close and innerNext 
which could cause a memory leak. Haven't had a chance to dig further this week, 
so I will try to wrap this up next week.


> PartitionSenderRootExec can leak memory because close method is not 
> synchronized
> --------------------------------------------------------------------------------
>
>                 Key: DRILL-6125
>                 URL: https://issues.apache.org/jira/browse/DRILL-6125
>             Project: Apache Drill
>          Issue Type: Bug
>    Affects Versions: 1.13.0
>            Reporter: Timothy Farkas
>            Assignee: Timothy Farkas
>            Priority: Minor
>             Fix For: 1.13.0
>
>
> PartitionSenderRootExec creates a PartitionerDecorator and saves it in the 
> *partitioner* field. The creation of the partitioner happens in the 
> createPartitioner method. This method get's called by the main fragment 
> thread. The partitioner field is accessed by the fragment thread during 
> normal execution but it can also be accessed by the receivingFragmentFinished 
> method which is a callback executed by the event processor thread. Because 
> multiple threads can access the partitioner field synchronization is done on 
> creation and on when receivingFragmentFinished. However, the close method can 
> also be called by the event processor thread, and the close method does not 
> synchronize before accessing the partitioner field. Since synchronization is 
> not done the event processor thread may have an old reference to the 
> partitioner when a query cancellation is done. Since it has an old reference 
> the current partitioner can may not be cleared and a memory leak may occur.



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