RFR (S): JDK-8027428: Different conditions for printing taskqueue statistics for parallel gc, parNew and G1

[Bengt Rutisson]

Hi Sangheon,

On 2014-09-30 01:30, Sangheon Kim wrote:
> Hi all,
>
> can I have reviews for the following small change to print taskqueue 
> statistics
> for parallel gc, parNew and G1?
> Main changes are:
> 1) printing by 'ParallelGCVerbose' flag, not 'PrintGCDetails && 
> ParallelGCVerbose'.
> 2) printing logs via 'gclog_or_tty', not 'tty'.
> 3) adding 'totals' row to sums up.
>
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8027428
>
> Webrev:
> http://cr.openjdk.java.net/~jwilhelm/8027428/

Thanks for fixing this. Could you provide some examples of what the 
output looks like for the different GCs now? It would make it easier to 
review this if I had examples of the output for ParNew, ParallelGC and G1.

I'm also wondering if we can have an even more descriptive declaration 
of ParallelGCVerbose in globals.hpp. With your change it says:

1532   product(bool, ParallelGCVerbose, 
false,                                   \
1533           "Print verbose collection statistics output for 
parallel"         \
1534 "collectors")                                                     \

But there is a lot of logging that has to do with parallel work (at 
least in G1) that is not controlled by this flag. It seems to me that 
the flag actually only controls the task queue statistics. Ideally we 
could change the name of the flag, but that will be too much overhead I 
guess. But we can maybe updated the description to indicate more what it 
actually controls.

Thanks,
Bengt

>
> Testing: jprt
>
> Thanks,
> Sangheon