RFR: 8212107: VMThread issues and cleanup [v2]

[Robbin Ehn]

On Tue, 22 Sep 2020 21:02:10 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Robbin Ehn 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 12 additional commits since
>> the last revision:
>>  - Merge branch 'master' into 8212107-vmthread
>>  - Fixed nits
>>  - Merge branch 'master' into 8212107-vmthread
>>  - Fixes after review from shipilev.
>>  - Fixed some indent misses
>>  - Fixed ws
>>  - Added assert
>>  - Restructured and simplified
>>  - Removed used linking in VM_Operation
>>  - Removed ticket and use only one Monitor
>>  - ... and 2 more: https://git.openjdk.java.net/jdk/compare/f6984edd...e49178a4
>
> src/hotspot/share/runtime/vmThread.cpp line 357:
> 
>> 355:   // _next_vm_operation is cleared holding VMOperation_lock
>> 356:   // after it have been executed.
>> 357:   while (_next_vm_operation == op) {
> 
> // Wait until the operation has been processed
> 
> But can this operation still be being processed as the current process?
> 
> Anyway can you add a couple of comments to help the reader.

Not while you have the VMOperation_lock. It can only get processed once you release it with wait().

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PR: https://git.openjdk.java.net/jdk/pull/228