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https://issues.apache.org/jira/browse/DRILL-6125?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16391959#comment-16391959
 ] 

ASF GitHub Bot commented on DRILL-6125:
---------------------------------------

Github user vrozov commented on a diff in the pull request:

    https://github.com/apache/drill/pull/1105#discussion_r173303074
  
    --- Diff: 
exec/java-exec/src/main/java/org/apache/drill/exec/work/fragment/FragmentExecutor.java
 ---
    @@ -488,47 +527,66 @@ void receiverFinished(FragmentHandle handle) {
           sendEvent(new FragmentEvent(EventType.RECEIVER_FINISHED, handle));
         }
     
    +    /**
    +     * Tell the {@link FragmentEventProcessor} not to process anymore 
events. This keeps stray cancellation requests
    +     * from being processed after the root has finished running and 
interrupts in the root thread have been cleared.
    +     */
    +    public synchronized void terminate() {
    +      terminate.set(true);
    +    }
    +
         @Override
         protected void processEvent(FragmentEvent event) {
    +      if (terminate.get()) {
    --- End diff --
    
    use atomic compare and set to avoid race condition.


> 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: 1.14.0
>
>
> 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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