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https://issues.apache.org/jira/browse/FLINK-35489?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17850953#comment-17850953
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Nicolas Fraison commented on FLINK-35489:
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[~mxm] what do you think about providing memory to the METASPACE_MEMORY before
the HEAP_MEMORY (switching those lines
[https://github.com/apache/flink-kubernetes-operator/blob/main/flink-autoscaler/src/main/java/org/apache/flink/autoscaler/tuning/MemoryTuning.java#L128-L131)]
And also ensuring that the METASPACE_MEMORY computed will never be bigger than
the one assigned by default (from config taskmanager.memory.jvm-metaspace.size)
Looks to me that this space should not grow with some load change and the
default one must be sufficiently big to have the TaskManager running fine. The
autotuning should only scale down this memory space depending on the usage, no?
> 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
>
> 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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