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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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