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https://issues.apache.org/jira/browse/YARN-7962?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16425525#comment-16425525
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BELUGA BEHR commented on YARN-7962:
-----------------------------------

[~wilfreds] {{try...finally}} is a best practice.

bq. It is recommended practice to always immediately follow a call to lock with 
a try block, most typically in a before/after construction

https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/locks/ReentrantLock.html

Please consider patch version 3 for inclusion into the project.

> Race Condition When Stopping DelegationTokenRenewer
> ---------------------------------------------------
>
>                 Key: YARN-7962
>                 URL: https://issues.apache.org/jira/browse/YARN-7962
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: resourcemanager
>    Affects Versions: 3.0.0
>            Reporter: BELUGA BEHR
>            Priority: Minor
>         Attachments: YARN-7962.1.patch, YARN-7962.2.patch, YARN-7962.3.patch, 
> YARN-7962.4.patch
>
>
> [https://github.com/apache/hadoop/blob/69fa81679f59378fd19a2c65db8019393d7c05a2/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/security/DelegationTokenRenewer.java]
> {code:java}
>   private ThreadPoolExecutor renewerService;
>   private void processDelegationTokenRenewerEvent(
>       DelegationTokenRenewerEvent evt) {
>     serviceStateLock.readLock().lock();
>     try {
>       if (isServiceStarted) {
>         renewerService.execute(new DelegationTokenRenewerRunnable(evt));
>       } else {
>         pendingEventQueue.add(evt);
>       }
>     } finally {
>       serviceStateLock.readLock().unlock();
>     }
>   }
>   @Override
>   protected void serviceStop() {
>     if (renewalTimer != null) {
>       renewalTimer.cancel();
>     }
>     appTokens.clear();
>     allTokens.clear();
>     this.renewerService.shutdown();
> {code}
> {code:java}
> 2018-02-21 11:18:16,253  FATAL org.apache.hadoop.yarn.event.AsyncDispatcher: 
> Error in dispatcher thread
> java.util.concurrent.RejectedExecutionException: Task 
> org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer$DelegationTokenRenewerRunnable@39bddaf2
>  rejected from java.util.concurrent.ThreadPoolExecutor@5f71637b[Terminated, 
> pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 15487]
>       at 
> java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:2048)
>       at 
> java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:821)
>       at 
> java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1372)
>       at 
> org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer.processDelegationTokenRenewerEvent(DelegationTokenRenewer.java:196)
>       at 
> org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer.applicationFinished(DelegationTokenRenewer.java:734)
>       at 
> org.apache.hadoop.yarn.server.resourcemanager.RMAppManager.finishApplication(RMAppManager.java:199)
>       at 
> org.apache.hadoop.yarn.server.resourcemanager.RMAppManager.handle(RMAppManager.java:424)
>       at 
> org.apache.hadoop.yarn.server.resourcemanager.RMAppManager.handle(RMAppManager.java:65)
>       at 
> org.apache.hadoop.yarn.event.AsyncDispatcher.dispatch(AsyncDispatcher.java:177)
>       at 
> org.apache.hadoop.yarn.event.AsyncDispatcher$1.run(AsyncDispatcher.java:109)
>       at java.lang.Thread.run(Thread.java:745)
> {code}
> What I think is going on here is that the {{serviceStop}} method is not 
> setting the {{isServiceStarted}} flag to 'false'.
> Please update so that the {{serviceStop}} method grabs the 
> {{serviceStateLock}} and sets {{isServiceStarted}} to _false_, before 
> shutting down the {{renewerService}} thread pool, to avoid this condition.



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