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https://issues.apache.org/jira/browse/FLINK-35489?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17853606#comment-17853606
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Maximilian Michels commented on FLINK-35489:
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Hey [~ashangit]! Good idea to switch the order between busgeting heap and
metaspace, but metaspace should be allowed to grow and not be fixed. The reason
is that metaspace is often configured too low. We can prevent metaspace related
errors by detecting and increasing metaspace.
> Metaspace size can be too little after autotuning change memory setting
> -----------------------------------------------------------------------
>
> Key: FLINK-35489
> URL: https://issues.apache.org/jira/browse/FLINK-35489
> Project: Flink
> Issue Type: Improvement
> Components: Kubernetes Operator
> Affects Versions: 1.8.0
> Reporter: Nicolas Fraison
> Priority: Major
> Labels: pull-request-available
>
> We have enable the autotuning feature on one of our flink job with below
> config
> {code:java}
> # Autoscaler configuration
> job.autoscaler.enabled: "true"
> job.autoscaler.stabilization.interval: 1m
> job.autoscaler.metrics.window: 10m
> job.autoscaler.target.utilization: "0.8"
> job.autoscaler.target.utilization.boundary: "0.1"
> job.autoscaler.restart.time: 2m
> job.autoscaler.catch-up.duration: 10m
> job.autoscaler.memory.tuning.enabled: true
> job.autoscaler.memory.tuning.overhead: 0.5
> job.autoscaler.memory.tuning.maximize-managed-memory: true{code}
> During a scale down the autotuning decided to give all the memory to to JVM
> (having heap being scale by 2) settting taskmanager.memory.managed.size to 0b.
> Here is the config that was compute by the autotuning for a TM running on a
> 4GB pod:
> {code:java}
> taskmanager.memory.network.max: 4063232b
> taskmanager.memory.network.min: 4063232b
> taskmanager.memory.jvm-overhead.max: 433791712b
> taskmanager.memory.task.heap.size: 3699934605b
> taskmanager.memory.framework.off-heap.size: 134217728b
> taskmanager.memory.jvm-metaspace.size: 22960020b
> taskmanager.memory.framework.heap.size: "0 bytes"
> taskmanager.memory.flink.size: 3838215565b
> taskmanager.memory.managed.size: 0b {code}
> This has lead to some issue starting the TM because we are relying on some
> javaagent performing some memory allocation outside of the JVM (rely on some
> C bindings).
> Tuning the overhead or disabling the scale-down-compensation.enabled could
> have helped for that particular event but this can leads to other issue as it
> could leads to too little HEAP size being computed.
> It would be interesting to be able to set a min memory.managed.size to be
> taken in account by the autotuning.
> What do you think about this? Do you think that some other specific config
> should have been applied to avoid this issue?
>
> Edit see this comment that leads to the metaspace issue:
> https://issues.apache.org/jira/browse/FLINK-35489?focusedCommentId=17850694&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-17850694
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