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https://issues.apache.org/jira/browse/FLINK-13477?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16902884#comment-16902884
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Xintong Song commented on FLINK-13477:
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Hi [~b.hanotte],
FYI, the FLIP [1] I mentioned has been posted. We do have a few open questions
at the moment, and the max direct memory size parameter is one of them. Please
join the discussion in the dev ML if you would like to.
Thank you~
[1]
[https://cwiki.apache.org/confluence/display/FLINK/FLIP-49%3A+Unified+Memory+Configuration+for+TaskExecutors]
> Containerized TaskManager killed because of lack of memory overhead
> -------------------------------------------------------------------
>
> Key: FLINK-13477
> URL: https://issues.apache.org/jira/browse/FLINK-13477
> Project: Flink
> Issue Type: Improvement
> Components: Deployment / Mesos, Deployment / YARN
> Affects Versions: 1.9.0
> Reporter: Benoit Hanotte
> Priority: Minor
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Currently, the `-XX:MaxDirectMemorySize` parameter is set as:
> `MaxDirectMemorySize = containerMemoryMB - heapSizeMB`
> (see
> [https://github.com/apache/flink/blob/7fec4392b21b07c69ba15ea554731886f181609e/flink-runtime/src/main/java/org/apache/flink/runtime/clusterframework/ContaineredTaskManagerParameters.java#L162])
> However as explained at
> https://docs.oracle.com/javase/8/docs/technotes/tools/unix/java.html,
> `MaxDirectMemorySize` only sets the maximum amount of memory that can be
> used for direct buffers, thus the amount of off-heap memory used can be
> greater than that value, leading to the container being killed by Mesos
> or Yarn as it exceeds the allocated memory.
> In addition, users might want to allocate off-heap memory through native
> code, in which case they will want to keep some of the container memory
> free and unallocated by Flink.
> To solve this issue, we currently set the following parameter:
> {code:java}
> -Dcontainerized.taskmanager.env.FLINK_ENV_JAVA_OPTS='-XX:MaxDirectMemorySize=600m'
> {code}
> which overrides the value that Flink picks (744M in this case) with a lower
> one to keep some overhead memory in the TaskManager containers. However this
> is an "ugly" hack as it goes around the clever memory allocation that Flink
> performs and allows to bypass the sanity checks done in
> `ContaineredTaskManagerParameters`.
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