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https://issues.apache.org/jira/browse/FLINK-19125?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17237356#comment-17237356
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Yun Tang commented on FLINK-19125:
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[~NicoK] I think we could add documentation at
[https://ci.apache.org/projects/flink/flink-docs-master/ops/deployment/docker.html]
> Avoid memory fragmentation when running flink docker image
> ----------------------------------------------------------
>
> Key: FLINK-19125
> URL: https://issues.apache.org/jira/browse/FLINK-19125
> Project: Flink
> Issue Type: Improvement
> Components: Deployment / Kubernetes, Runtime / State Backends
> Affects Versions: 1.12.0, 1.11.1
> Reporter: Yun Tang
> Assignee: Yun Tang
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.12.0, 1.11.3
>
>
> This ticket tracks the problem of memory fragmentation when launching default
> Flink docker image.
> In FLINK-18712, user reported if he submits job with rocksDB state backend on
> a k8s session cluster again and again once it finished, the memory usage of
> task manager grows continuously until OOM killed.
> I reproduce this problem with official Flink docker image no matter how we
> use rocksDB (whether to enable managed memory or not).
> I dig into the problem and found this is due to the memory fragmentation
> caused by {{glibc}}, which would not return memory to kernel gracefully
> (please refer to [glibc
> bugzilla|https://sourceware.org/bugzilla/show_bug.cgi?id=15321] and [glibc
> manual|https://www.gnu.org/software/libc/manual/html_mono/libc.html#Freeing-after-Malloc])
> I found limiting MALLOC_ARENA_MAX to 2 could mitigate this problem (please
> refer to
> [choose-for-malloc_arena_max|https://devcenter.heroku.com/articles/tuning-glibc-memory-behavior#what-value-to-choose-for-malloc_arena_max]
> for more details).
> And if we choose to use jemalloc to allocate memory via rebuilding another
> docker image, the problem would be gone.
> {code:java}
> apt-get -y install libjemalloc-dev
> ENV LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libjemalloc.so
> {code}
> Jemalloc intends to [emphasize fragmentation
> avoidance|https://github.com/jemalloc/jemalloc/wiki/Background#intended-use]
> and we might consider to re-factor our Dockerfile to base on jemalloc to
> avoid memory fragmentation.
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