[jdk17u-dev] RFR: 8319876: Reduce memory consumption of VM_ThreadDump::doit

[Paul Hohensee]

On Tue, 30 Sep 2025 16:24:51 GMT, Elif Aslan <duke at openjdk.org> wrote:

> This pull request contains a backport of commit [8ec6b8de3bb3d7aeebdcb45d761b18cce3bab75e](https://github.com/openjdk/jdk/commit/8ec6b8de3bb3d7aeebdcb45d761b18cce3bab75e) from the openjdk/jdk repository to JDK 17.
> 
> This backport significantly reduces RSS memory usage during ThreadMXBean.dumpAllThreads(boolean, boolean) execution.
> 
> This is not a clean backport due to differences between JDK 17 and upstream:
> 
> Threading Context: Changed ResourceMark rm(VMThread::vm_thread()) to ResourceMark rm;
>    • Similar to [JDK 21 backport](https://github.com/openjdk/jdk21u-dev/pull/307)
> 
> Minor conflict resolved: _threads = nullptr; → _threads = NULL; to match JDK 17 conventions
> 
> GHA tested additionally ran tier1 tests on my local mac and passed.

Lgtm. Looks low risk, but I'd run tier2 on a bigger box to be on the safe side.

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Marked as reviewed by phh (Reviewer).

PR Review: https://git.openjdk.org/jdk17u-dev/pull/4006#pullrequestreview-3286109709