[jira] [Commented] (HADOOP-12313) Possible NPE in JvmPauseMonitor.stop()

["Junping Du (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-12313?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14681611#comment-14681611 ] 

Junping Du commented on HADOOP-12313:
-------------------------------------

bq. The "proper way" would be to synchronize both start()/stop() (in particular if restart is an expectation). Would you like an updated patch implementing?
I am not sure if restart is an expectation at the beginning. But theoretically, any services should be restartable. However, just double checked with other services, like: NodeManager, ResourceManager, etc., it seems like all these services are implemented as one time only service. So I am fine with keeping things like this to conform the same pattern with other services. I will file another separated JIRA to discuss restartable issue unless someone tells me a solid reason on this.
Based on above comments, we don't need to handle start() after stop() case, so "if (shouldRun) { monitorThread.start(); }" is not necessary or not sufficient (at least we should log some warn messages). Either way should be fine to me.


> Possible NPE in JvmPauseMonitor.stop()
> --------------------------------------
>
>                 Key: HADOOP-12313
>                 URL: https://issues.apache.org/jira/browse/HADOOP-12313
>             Project: Hadoop Common
>          Issue Type: Bug
>            Reporter: Rohith Sharma K S
>            Assignee: Gabor Liptak
>         Attachments: YARN-4035.1.patch
>
>
> It is observed that after YARN-4019 some tests are failing in TestRMAdminService with null pointer exceptions in build [build failure |https://builds.apache.org/job/PreCommit-YARN-Build/8792/artifact/patchprocess/testrun_hadoop-yarn-server-resourcemanager.txt]
> {noformat}
> unning org.apache.hadoop.yarn.server.resourcemanager.TestRMAdminService
> Tests run: 19, Failures: 0, Errors: 2, Skipped: 0, Time elapsed: 11.541 sec <<< FAILURE! - in org.apache.hadoop.yarn.server.resourcemanager.TestRMAdminService
> testModifyLabelsOnNodesWithDistributedConfigurationDisabled(org.apache.hadoop.yarn.server.resourcemanager.TestRMAdminService)  Time elapsed: 0.132 sec  <<< ERROR!
> java.lang.NullPointerException: null
> 	at org.apache.hadoop.util.JvmPauseMonitor.stop(JvmPauseMonitor.java:86)
> 	at org.apache.hadoop.yarn.server.resourcemanager.ResourceManager$RMActiveServices.serviceStop(ResourceManager.java:601)
> 	at org.apache.hadoop.service.AbstractService.stop(AbstractService.java:221)
> 	at org.apache.hadoop.yarn.server.resourcemanager.ResourceManager.stopActiveServices(ResourceManager.java:983)
> 	at org.apache.hadoop.yarn.server.resourcemanager.ResourceManager.transitionToStandby(ResourceManager.java:1038)
> 	at org.apache.hadoop.yarn.server.resourcemanager.ResourceManager.serviceStop(ResourceManager.java:1085)
> 	at org.apache.hadoop.service.AbstractService.stop(AbstractService.java:221)
> 	at org.apache.hadoop.service.AbstractService.close(AbstractService.java:250)
> 	at org.apache.hadoop.yarn.server.resourcemanager.TestRMAdminService.testModifyLabelsOnNodesWithDistributedConfigurationDisabled(TestRMAdminService.java:824)
> testRemoveClusterNodeLabelsWithDistributedConfigurationEnabled(org.apache.hadoop.yarn.server.resourcemanager.TestRMAdminService)  Time elapsed: 0.121 sec  <<< ERROR!
> java.lang.NullPointerException: null
> 	at org.apache.hadoop.util.JvmPauseMonitor.stop(JvmPauseMonitor.java:86)
> 	at org.apache.hadoop.yarn.server.resourcemanager.ResourceManager$RMActiveServices.serviceStop(ResourceManager.java:601)
> 	at org.apache.hadoop.service.AbstractService.stop(AbstractService.java:221)
> 	at org.apache.hadoop.yarn.server.resourcemanager.ResourceManager.stopActiveServices(ResourceManager.java:983)
> 	at org.apache.hadoop.yarn.server.resourcemanager.ResourceManager.transitionToStandby(ResourceManager.java:1038)
> 	at org.apache.hadoop.yarn.server.resourcemanager.ResourceManager.serviceStop(ResourceManager.java:1085)
> 	at org.apache.hadoop.service.AbstractService.stop(AbstractService.java:221)
> 	at org.apache.hadoop.service.AbstractService.close(AbstractService.java:250)
> 	at org.apache.hadoop.yarn.server.resourcemanager.TestRMAdminService.testRemoveClusterNodeLabelsWithDistributedConfigurationEnabled(TestRMAdminService.java:867)
> {noformat}



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