RFR: Reimplement TsanOopMap support using WeakHandle and ResizeableResourceHashtable [v4]

[Jiangli Zhou]

On Tue, 23 Jul 2024 01:23:40 GMT, Man Cao <manc at openjdk.org> wrote:

>> Jiangli Zhou has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Update TsanOopMap.hpp comment with more details.
>
> src/hotspot/share/tsan/tsanOopMap.cpp line 302:
> 
>> 300: 
>> 301:   {
>> 302:     MutexLocker mu(TsanOopMap_lock, Mutex::_no_safepoint_check_flag);
> 
> Do we really need this lock if it is called during a GC pause by only the VM thread? Currently it is called by multiple GC threads, so the lock might appear necessary.
> 
> Also see the comment in the old `TsanOopMap::weak_oops_do`. We should probably keep that comment.

We need the lock here as it's done in concurrent worker threads that handle the WeakProcessor::WeakOopsDoTasks.

As discussed offline today, doing the tsanOopMap processing and tsan notification in WeakProcessor::Task::work is cleaner and more maintainable than other possible alternatives.

-------------

PR Review Comment: https://git.openjdk.org/tsan/pull/19#discussion_r1688889861