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Posted to issues@flink.apache.org by "Nawaid Shamim (JIRA)" <ji...@apache.org> on 2018/12/19 15:48:00 UTC
[jira] [Commented] (FLINK-11205) Task Manager Metaspace Memory Leak
[ https://issues.apache.org/jira/browse/FLINK-11205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16725120#comment-16725120 ]
Nawaid Shamim commented on FLINK-11205:
---------------------------------------
*Workaround:* Copy Flink job JAR into /usr/lib/flink/lib and AppClassLoader will load all the required classes from classpath.
!Screenshot 2018-12-18 at 15.47.55.png!
> Task Manager Metaspace Memory Leak
> -----------------------------------
>
> Key: FLINK-11205
> URL: https://issues.apache.org/jira/browse/FLINK-11205
> Project: Flink
> Issue Type: Bug
> Affects Versions: 1.5.5, 1.6.2, 1.7.0
> Reporter: Nawaid Shamim
> Priority: Major
> Attachments: Screenshot 2018-12-18 at 12.14.11.png, Screenshot 2018-12-18 at 15.47.55.png
>
>
> Job Restarts causes task manager to dynamically load duplicate classes. Metaspace is unbounded and grows with every restart. YARN aggressively kill such containers but this affect is immediately seems on different task manager which results in death spiral.
> Task Manager uses dynamic loader as described in [https://ci.apache.org/projects/flink/flink-docs-stable/monitoring/debugging_classloading.html]
> {quote}
> *YARN*
> YARN classloading differs between single job deployments and sessions:
> * When submitting a Flink job/application directly to YARN (via {{bin/flink run -m yarn-cluster ...}}), dedicated TaskManagers and JobManagers are started for that job. Those JVMs have both Flink framework classes and user code classes in the Java classpath. That means that there is _no dynamic classloading_ involved in that case.
> * When starting a YARN session, the JobManagers and TaskManagers are started with the Flink framework classes in the classpath. The classes from all jobs that are submitted against the session are loaded dynamically.
> {quote}
> The above is not entirely true specially when you set {{-yD classloader.resolve-order=parent-first}} . We also above observed the above behaviour when submitting a Flink job/application directly to YARN (via {{bin/flink run -m yarn-cluster ...}}).
> !Screenshot 2018-12-18 at 12.14.11.png!
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