RFR: 8357481: Excessive CompileTask wait/notify monitor creation [v2]

[Dean Long]

On Fri, 23 May 2025 17:28:38 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> See bug for rationale.
>> 
>> This PR implements the 2nd solution from the bug: lift the lock to be global. As described in the bug, excess locking work would realistically affect Xcomp, and only in a minor way. But we will reap a minor footprint/latency benefit by not constructing the lock for every `CompileTask`.
>> 
>> Additional testing:
>>  - [x] Linux x86_64 server fastdebug, `compiler`
>>  - [x] Linux x86_64 server fastdebug, `all`
>>  - [x] Linux AArch64 server fastdebug, `all`
>
> Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:
> 
>  - Merge branch 'master' into JDK-8357481-compile-task-lock
>  - Fix

Isn't it true that we only have one CompileTask per CompilerThread?  Would it make sense to move this monitor into the CompilerThread instead?

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PR Comment: https://git.openjdk.org/jdk/pull/25364#issuecomment-2905858353