RFR(S): 7099824: G1: we should take the pending list lock before doing the remark pause

[Ramki Ramakrishna]

Hi John -- This looks good to me, although I didn't see any obvious 
reason to make clean up pauses take the
PLL lock given they do not mess with the pending list in any manner. 
Otherwise looks good to me.

-- ramki

On 10/17/2011 2:36 PM, John Cuthbertson wrote:
> Hi Everyone,
>
> Can I have a couple of volunteers review these changes? The webrev can 
> be found at: http://cr.openjdk.java.net/~johnc/7099824/wevrev.0/
>
> Summary: During a G1 remark pause, the JVM may enqueue some discovered 
> references on to the pending list. Whenever the JVM modifies the 
> pending list, it is supposed to synchronize with the ReferenceHandler 
> thread and acquire the pending list lock but G1's concurrent GC 
> operations were not doing so.
>
> Testing: the GC test suite with both CMS and G1, and jprt.
>
> Thanks,
>
> JohnC