RFR(S) 8206467: Refactor G1ParallelCleaningTask into shared

[Zhengyu Gu]

>> We have a (closed) test that deadlocks 100% because of that.
> 
> I don't know I made functional change here.
> 
> I don't see JDK-8206423 pushed. But it should remove 
> ResolvedMethodCleaningTask from parallel cleaning anyway, and move to 
> ServiceThread, do I miss something here?

Oops, it did go in ahead of me.

> 
>>
>> I try to follow up with an RFR asap that removes that task, if that
>> takes too long I will revert the whole change.
Sorry about this. Let me know if I can help.

-Zhengyu

>>
>> And, please, in the future, when introducing code sharing changes,
>> please split refactoring changes (moving code around) and functionality
>> changes.
> 
> Okay.
> 
> Thanks,
> 
> -Zhengyu
> 
>>
>> That would have made it a lot easier to spot this issue during review.
>>
>> Also we really want to sit down about how to measure time in our code:
>> this change introduces *another* time base (us) using *another* base
>> type (jint) without adding support for existing collectors (i.e. G1;
>> *without* even filing an RFE to add this). This would also have been
>> spotted easily if the reviews for old/new functionality were separated.
>>
>> Thanks,
>>    Thomas
>>