RFR: 8356870: HotSpotDiagnosticMXBean.dumpThreads and jcmd Thread.dump_to_file updates [v5]

[Serguei Spitsyn]

On Tue, 3 Jun 2025 19:20:52 GMT, Alan Bateman <alanb at openjdk.org> wrote:

>> Updates the thread dump generated by HotSpotDiagnosticMXBean.dumpThreads and jcmd Thread.dump_to_file to include thread state and lock information. Also update the HotSpotDiagnosticMXBean.dumpThreads API description to link to a description of the JSON format dump as that format is intended to be parseable/read by tools.
>> 
>> This PR is dependent on [pull/25425](https://github.com/openjdk/jdk/pull/25425). As noted in that PR, the changes accumulated in the loom repo, and have been split up to make it easier to review.
>> 
>> The changes include some re-implementation of ThreadDumper. This is because it used PrintStream and didn't fail if there was an I/O error, e.g. file system full. Furthermore, the indentation to pretty print the json was fragile and hard to maintain so this is changed to use a supporting writer class to do this.
>> 
>> Test coverage is significantly expanded, including updating the test library that is used by several tests to parse the thread dump.
>> 
>> Testing: tier1-6
>
> Alan Bateman has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 19 commits:
> 
>  - Merge branch 'master' into JDK-8356870
>  - Sync up from loom repo, includes review comments
>  - Merge branch 'pull/25425' into JDK-8356870
>  - typo
>  - feedback
>  - Update src/hotspot/share/services/threadService.cpp
>    
>    Co-authored-by: David Holmes <62092539+dholmes-ora at users.noreply.github.com>
>  - Temp fixed until fixed in pull/25425
>  - Sync up from loom repo, includes review comments
>  - Merge branch 'pull/25425' into JDK-8356870
>  - removed retry_handshake logic
>  - ... and 9 more: https://git.openjdk.org/jdk/compare/406f1bc5...127814d9

Marked as reviewed by sspitsyn (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/25429#pullrequestreview-2893843780