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https://issues.apache.org/jira/browse/YARN-505?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13674208#comment-13674208
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Niranjan Singh commented on YARN-505:
-------------------------------------
The NPE is in the LinkedBlockingQueue class of JDK.
In handler.handle(null), the event which is null in this case is put in
LinkedBlockingQueue ,
without checking whether the event is null or not.
eventQueue.put(event);line 188 of org.apache.hadoop.yarn.event.AsyncDispatcher.
One solution could be to check for null when event is put in eventQueue below.
if(event != null){
eventQueue.put(event);
}else{
LOG.warn("Event cannot be null"+event);
}
> NPE at AsyncDispatcher$GenericEventHandler
> ------------------------------------------
>
> Key: YARN-505
> URL: https://issues.apache.org/jira/browse/YARN-505
> Project: Hadoop YARN
> Issue Type: Improvement
> Components: resourcemanager
> Affects Versions: 3.0.0
> Reporter: Przemyslaw Pretki
> Priority: Minor
>
> Steps to reproduce:
> {code}
> @Test
> public void testAsyncDispatcher()
> {
> AsyncDispatcher dispatcher = new AsyncDispatcher();
> EventHandler handler = dispatcher.getEventHandler();
> handler.handle(null);
> }
> {code}
> Moreover, event taken from *BlockingQueue* will never be *null*, so that it
> seems that the following condition is not necessary
> (AsyncDispatcher.createThread() method):
> {code}
> if (event != null) {
> dispatch(event);
> }
> {code}
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