8327864: Support segmented heap dump for HotSpotDiagnosticMXBean

[y1yang0]

We've received feedback from users of cloud APM platform wanting the new version of the JDK to allow the HotSpotDiagnosticMXBean.dumpHeap underpinnings to reduce STW time using sgemented heapdump. Supporting segmented heapdump for mxbean is a reasonable requirement and adds little additional complexity, both in terms of maintainability and understanding.

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Progress

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Issue

• JDK-8327864: Support segmented heap dump for HotSpotDiagnosticMXBean (Bug - P4) ⚠️ Issue is not open.

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[bridgekeeper[bot]]

:wave: Welcome back yyang! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk[bot]]

@y1yang0 The following labels will be automatically applied to this pull request:

• hotspot-runtime
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Webrevs

• 00: Full (21279b1f)

[openjdk[bot]]

❗ This change is not yet ready to be integrated. See the Progress checklist in the description for automated requirements.

[y1yang0]

Hi @kevinjwalls Thanks for your review! I was reminded by Alex that there is already a similar issue here ready to make two phase heap dump the default choice, so all we need is to simply change the default parallel parameter (and potential bug fix)

https://github.com/openjdk/jdk/blob/21279b1f652c54693e317d55e7da6478b959fdfb/src/hotspot/share/services/heapDumper.hpp#L64

I will first synergize with @alexmenkov to see if we can improve based on the current patch, or close the current PR and wait for his new one.

P.S. the phrase "two phase" makes sense to me:)

[kevinjwalls]

We should close this now the issue is marked as a duplicate, thanks!