RFR (S): 7129271 G1: Interference from multiple threads in PrintGC/PrintGCDetails output

[Tony Printezis]

Thanks John, ship it. :-)

On 01/13/2012 12:48 PM, John Cuthbertson wrote:
> Hi Tony,
>
> Thanks. Good point. I missed the print_heap_after_gc() call. Consider 
> it done.
>
> JohnC
>
> On 01/13/12 09:25, Tony Printezis wrote:
>> John,
>>
>> Thanks for taking into account my feedback! My only comment is that 
>> you should maybe move the doConcurrentMark() call to even further 
>> down (i.e., as the last thing we do in that method before return 
>> true;) given that there's still some output that can be generated 
>> after its current location (e.g., PrintHeapAtGC).
>>
>> Tony
>>
>> On 01/13/2012 12:11 PM, John Cuthbertson wrote:
>>> Hi Everyone,
>>>
>>> Based upon feedback from Tony, I have a much simpler version of this 
>>> change. The new changes can be found at: 
>>> http://cr.openjdk.java.net/~johnc/7129271/webrev.1/
>>>
>>> Thanks,
>>>
>>> JohnC
>>>
>>> On 01/12/12 11:28, John Cuthbertson wrote:
>>>> Hi Everyone,
>>>>
>>>> Can I have a couple of volunteers review the changes for this CR? 
>>>> The webrev can be found at: 
>>>> http://cr.openjdk.java.net/~johnc/7129271/webrev.0/
>>>>
>>>> The issue was that the when PrintGC or PrintGCDetails was enabled, 
>>>> during an initial pause, the "concurrent-mark-start" message from 
>>>> the ConcurrentMark thread was interfering with the output (by the 
>>>> VM thread) from the GC pause. This was adding a randomness and 
>>>> irregularity to the output that was making it difficult to parse. 
>>>> It was also seen more frequently when the GC logging output was 
>>>> directed to a file rather than stdout.
>>>>
>>>> The solution is to move the code that signals the Concurrent Mark 
>>>> thread to after when the output from the GC pause is complete.
>>>>
>>>> In the webrev, please ignore the counts of the number of lines 
>>>> changed. I added an inner scope and so indented a bunch of code 
>>>> which I think has confused the webrev tool. Fortunately the actual 
>>>> web diffs seem to have not included the extra whitespace.
>>>>
>>>> Testing: the GC test suite (with a low marking threshold - 2% to 
>>>> create lots of marking cycles)
>>>>
>>>> Thanks,
>>>>
>>>> JohnC
>>>>
>>>>
>>>
>