RFR: 8068971: A heap region being cleared should not belong to the cset

[Thomas Schatzl]

Hi Erik,

On Fri, 2015-01-16 at 08:47 +0100, Erik Helin wrote:
> Hi all,
> 
> this tiny patch ensures that a heap region being cleared via
> HeapRegion::hr_clear does not belong to the collection set. This has
> never been the case, because we are only clearing heap regions upon
> initialization (and then they don't belong to any cset) or from the
> cleanup phase of the concurrent marking. The cleanup phase will only
> call hr_clear on an old heap region, and an old heap region is only part
> of the cset during a mixed GC (which can't happen concurrently with the
> cleanup phase of concurrent marking).
> 
> Webrev:
> http://cr.openjdk.java.net/~ehelin/8068971/webrev.00/

  could you change the assert to something like:

+  assert(!_in_collection_set,
+         err_msg("Should not clear heap region %u in the collection set", hrm_index()));

to improve the error message?

Thanks,
  Thomas