G1 garbage collector help

[Junni Fan]

BTW, we are using jdk 7 118

On Sun, Sep 25, 2011 at 9:07 AM, Junni Fan <junnifan at gmail.com> wrote:
> Hey list, we used to use CMS for our java server. Our memory activity
> is very high, we use 4 CMS threads, and set initial fraction to 1 to
> aggressively collect old gen memory. The hardware we use has 72G
> memory and 8 core. The settings we use is:
>
> java -Xms64G -Xmx64G -Xmn256M -verbose:gc -XX:+PrintGCDateStamps
> -XX:+PrintGCDetails  -XX:+UseCMSInitiatingOccupancyOnly
> -XX:SurvivorRatio=8 -XX:TargetSurvivorRatio=90 -XX:+AggressiveOpts
> -XX:+UseParNewGC -XX:+UseConcMarkSweepGC
> -XX:CMSInitiatingOccupancyFraction=1 -XX:+CMSParallelRemarkEnabled
> -XX:ParallelCMSThreads=4
>
> But since CMS has the fragmentation problem the server occasionally
> goes to full GC still.
>
> So we are considerring to test our G1 collector. But appears that G1
> falls back to full GC even quicker. I set the following G1 params:
>
>  -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC
> -XX:MaxGCPauseMillis=200 -XX:GCPauseIntervalMillis=300
> -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=8
>
> It appears also that there are two marker threads and 8 refinement
> threads running, which does not seem aggressive enough ...
>
> Is there anyway that we can make G1 do more work? Like the option we
> had for CMS ParallelCMSThreads? Also are there good reads on G1? Like
> a comprehensive list of options that we can tune for G1 and what they
> are?
>
> Thanks a million!
>