RFR(s): 8029255: G1: Reference processing should not enqueue references on the shared SATB queue

[Bengt Rutisson]

Looks good, Per!

For the record, Per and I discussed a couple of different options to 
solve this issue but came to the conclusion that the current patch is 
the better option for now. Per will document the other options in the 
bug report.

Bengt


On 2013-11-28 17:50, Per Liden wrote:
> Summary: A side effect of fixing JDK-8029162 (G1: Shared SATB queue 
> never enabled) is that the reference processor will start to add 
> references to the shared SATB queue when enqueuing discovered 
> references. This will later cause 
> ConcurrentMark::verify_no_cset_oops() to fail because we now have 
> enqueued references in the SATB qeueue which points into the 
> collection set (which will be empty after the collection). This patch 
> makes sure we avoid doing pre-barriers, by instead doing raw stores 
> followed by a post-barrier.
>
> This patch also removes an unused constructor and the unnecessary 
> caching of the barrier set in the ReferenceProcessor. So use of _bs 
> was replaced by oopDesc::bs(). Further, the cached barrier set was 
> only set/used if discovered_list_needs_barrier was true, but with this 
> change we will need the barrier set in other cases too.
>
> Testing done: jprt, kitchensink (10 hours), gcbasher (10 hours)
>
> http://cr.openjdk.java.net/~pliden/8029255/webrev.0/
>
> https://bugs.openjdk.java.net/browse/JDK-8029255
>
> cheers,
> /Per