RFR: 8150518: G1 GC crashes at G1CollectedHeap::do_collection_pause_at_safepoint(double)

[Jon Masamitsu]

On 03/16/2016 04:40 AM, Thomas Schatzl wrote:
> Hi,
>
> On Tue, 2016-03-15 at 15:23 -0700, Jon Masamitsu wrote:
>> On 3/15/2016 6:37 AM, Fairoz Matte wrote:
>>> Hi Jon, David, Sangheon, Kim and Thomas,
>>>
>>> Thanks for your review comments.
>>> Patch is modified to incorporate the changes
>>> @@ -1675,9 +1675,8 @@
>>>      FLAG_SET_DEFAULT(ParallelGCThreads,
>>>                        
>>>   Abstract_VM_Version::parallel_worker_threads());
>>>      if (ParallelGCThreads == 0) {
>>> -    FLAG_SET_DEFAULT(ParallelGCThreads,
>>> -
>>>   Abstract_VM_Version::parallel_worker_threads());
>>> -  }
>>> +    vm_exit_during_initialization("The flag -XX:+UseG1GC can not
>>> be combined with -XX:ParallelGCThreads=0", NULL);
>>> +    }
>>>
>>> Find below is the details
>>> Bugid - https://bugs.openjdk.java.net/browse/JDK-8150518
>>> Webrev - http://cr.openjdk.java.net/~rpatil/8150518/webrev.01/
>> Looks good.
>    fine with me, but we probably need to prepare some release note about
> that behavioral change.

I added the label release-note=yes and the comment

> For release notes
>
> With UseG1GC specifying -XX:ParallelGCThreads=0 is no longer allowed. 
> Previously with -XX:ParallelGCThreads=0 G1 would execute some tasks 
> using serial code executed by the VM thread. The closest approximation 
> to this behavior is to specify -XX:ParallelGCThreads=1 which will 
> cause parallel tasks to be executed by a single GC worker thread using 
> parallel code. 

Please feel free to edit that comment.

Jon


>
> Thanks,
>    Thomas