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https://issues.apache.org/jira/browse/YARN-8382?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16496869#comment-16496869
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Miklos Szegedi commented on YARN-8382:
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Thank you for the patch [~ziqian hu].
I think you can just use {{Math.min}} for your logic.
This can still cause an issue, since the sigkill logic may have some residual
delay racing with deleting the cgroups. Probably the right apporoach would be
to set the cgroup delete delay to sigkill timeout + 1 second +
NM_LINUX_CONTAINER_CGROUPS_DELETE_TIMEOUT. The cgroups timeout is there
probably to address the issues due to clean up after the last thread has exited.
Please address the checkstyle issues.
> cgroup file leak in NM
> ----------------------
>
> Key: YARN-8382
> URL: https://issues.apache.org/jira/browse/YARN-8382
> Project: Hadoop YARN
> Issue Type: Bug
> Components: nodemanager
> Environment: we write an container with a shutdownHook which has a
> piece of code like "while(true) sleep(100)" . when
> *yarn.nodemanager.linux-container-executor.cgroups.delete-timeout-ms <*
> *yarn.nodemanager.sleep-delay-before-sigkill.ms , cgourp file leak happens;
> when* *yarn.nodemanager.linux-container-executor.cgroups.delete-timeout-ms >*
> ** *yarn.nodemanager.sleep-delay-before-sigkill.ms, cgroup file is deleted
> successfully***
> Reporter: Hu Ziqian
> Assignee: Hu Ziqian
> Priority: Major
> Attachments: YARN-8382-branch-2.8.3.001.patch, YARN-8382.001.patch
>
>
> As Jiandan said in YARN-6525, NM may delete Cgroup container file timeout
> with logs like below:
> org.apache.hadoop.yarn.server.nodemanager.util.CgroupsLCEResourcesHandler:
> Unable to delete cgroup at: /cgroup/cpu/hadoop-yarn/container_xxx, tried to
> delete for 1000ms
>
> we found one situation is that when we set
> *yarn.nodemanager.sleep-delay-before-sigkill.ms* bigger than
> *yarn.nodemanager.linux-container-executor.cgroups.delete-timeout-ms*, the
> cgroup file leak happens *.*
>
> One container process tree looks like follow graph:
> bash(16097)───java(16099)─┬─\{java}(16100)
> ├─\{java}(16101)
> {{ ├─\{java}(16102)}}
>
> {{when NM kills a container, NM sends kill -15 -pid to kill container process
> group. Bash process will exit when it received sigterm, but java process may
> do some job (shutdownHook etc.), and doesn't exit unit receive sigkill. And
> when bash process exits, CgroupsLCEResourcesHandler begin to try to delete
> cgroup files. So when
> *yarn.nodemanager.linux-container-executor.cgroups.delete-timeout-ms*
> arrived, the java processes may still running and cgourp/tasks still not
> empty and cause a cgroup file leak.}}
>
> {{we add a condition that
> *yarn.nodemanager.linux-container-executor.cgroups.delete-timeout-ms* must
> bigger than *yarn.nodemanager.sleep-delay-before-sigkill.ms* to solve this
> problem.}}
>
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