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https://issues.apache.org/jira/browse/LUCENE-9196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17033543#comment-17033543
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Robert Muir commented on LUCENE-9196:
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I think the idea here is that jenkins will pass its own VM options anyway to
specify the garbage collector it wants and stuff. So it will basically override
all of our defaults.
> look into adding -XX:ActiveProcessorCount=1 to parallel build jvms
> ------------------------------------------------------------------
>
> Key: LUCENE-9196
> URL: https://issues.apache.org/jira/browse/LUCENE-9196
> Project: Lucene - Core
> Issue Type: Task
> Components: general/build
> Reporter: Robert Muir
> Priority: Major
>
> I've been using this in my own gradle.properties (both for test and gradle
> vms).
> I think otherwise there may be a bad multiplicative effect at play: if you
> have N (say 16 cores), the build defaults to using 8 parallel resources. But
> each of these jvms uses ergonomic defaults to size stuff like compiler/gc
> threads according to the entire machine. Similar to the reasons behind
> container support, etc.
> I tell each build/test JVM to pretend like it runs on 1 cpu machine with this
> flag. It seems to give a lower load average when running tests? Something to
> look into.
> {quote}
> -XX:ActiveProcessorCount=x
> Overrides the number of CPUs that the VM will use to calculate
> the size of thread pools it will use for various operations such
> as Garbage Collection and ForkJoinPool.
> The VM normally determines the number of available processors
> from the operating system. This flag can be useful for parti‐
> tioning CPU resources when running multiple Java processes in
> docker containers. This flag is honored even if UseContainer‐
> Support is not enabled. See -XX:-UseContainerSupport for a de‐
> scription of enabling and disabling container support.
> {quote}
> cc [~dweiss]
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