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

[John Cuthbertson]

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
>
>