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[9.1] Bypass MMap arena grouping as this has caused issues with too many regions being mapped (#135012) #135115

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Merged
merged 1 commit into from
Sep 19, 2025
Merged

[9.1] Bypass MMap arena grouping as this has caused issues with too many regions being mapped (#135012) #135115

merged 1 commit into from
Sep 19, 2025

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Backports the following commits to 9.1:

@benwtrent
Bypass MMap arena grouping as this has caused issues with too many re…
50ad283 
…gions being mapped (elastic#135012)

There is a JDK issue where closing sharedArenas from many threads can
significantly harm performance. 

This ref-counting of shared arenas was designed as a way to get around
this performance issue. However, we have noticed a significant increase
in leaks and issues with mmap regions since this change. 

https://bugs.openjdk.org/browse/JDK-8335480 should have helped the
performance impact of closing shared arenas (though possibly not fully
mitigated it).

I am proposing we turn off the grouping as it appears (at least to me),
not worth it. 

I am willing to backdown if we thing other fixes should be done.

I also suggest this gets backported to 9.1, 8.19, and is merged into 9.2
@benwtrent benwtrent requested a review from a team as a code owner September 19, 2025 22:52
@benwtrent benwtrent added :Core/Infra/Core Core issues without another label :Distributed Indexing/Distributed A catch all label for anything in the Distributed Indexing Area. Please avoid if you can. :Search/Search Search-related issues that do not fall into other categories >bug auto-merge-without-approval Automatically merge pull request when CI checks pass (NB doesn't wait for reviews!) backport Team:Core/Infra Meta label for core/infra team Team:Distributed Indexing Meta label for Distributed Indexing team Team:Search Meta label for search team labels Sep 19, 2025
@elasticsearchmachine elasticsearchmachine mentioned this pull request Sep 19, 2025
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@elasticsearchmachine elasticsearchmachine merged commit 2b13cff into elastic:9.1 Sep 19, 2025
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@benwtrent benwtrent deleted the backport/9.1/pr-135012 branch September 19, 2025 23:56
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auto-merge-without-approval Automatically merge pull request when CI checks pass (NB doesn't wait for reviews!) backport >bug :Core/Infra/Core Core issues without another label :Distributed Indexing/Distributed A catch all label for anything in the Distributed Indexing Area. Please avoid if you can. :Search/Search Search-related issues that do not fall into other categories Team:Core/Infra Meta label for core/infra team Team:Distributed Indexing Meta label for Distributed Indexing team Team:Search Meta label for search team v9.1.5

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@benwtrent @elasticsearchmachine