RFR: 8291714: Implement a Multi-Reader Single-Writer mutex for Hotspot [v4]

[Johan Sjölén]

On Thu, 25 Aug 2022 16:23:41 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> Johan Sjölén has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains six commits:
>> 
>>  - Fix tests for updated threadHelper
>>  - Remove outdated threadHelper
>>  - Update documentation
>>  - Fix outdated headers and remove dead code
>>  - Review comments
>>  - Implement MRSWMutex
>
> src/hotspot/share/utilities/readWriteLock.hpp line 82:
> 
>> 80:   //
>> 81:   volatile int32_t _count;
>> 82: 
> 
> This class should be noncopyable.  Maybe it is implicitly so via the `PlatformMonitor` member, but would be better to be explicit.

It is! See L54.

> src/hotspot/share/utilities/readWriteLock.hpp line 89:
> 
>> 87:   }
>> 88: 
>> 89:   ~ReadWriteLock() {
> 
> Use default destructor (either implicit or explicit) rather than empty body destructor.

Good point, made it explicit.

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PR: https://git.openjdk.org/jdk/pull/9838