Sudden permanent increase in Minor (ParNew) GC time, that only a stop-the-world System.gc() alleviates

[Srinivas Ramakrishna]

Check to see if the pause time increase correlates to a jump in the
promotion volume per scavenge. Should be easy to get from yr gc logs (which
i haven't looked at).

-- ramki



On Sun, Jan 27, 2013 at 12:34 AM, Pas <pasthelod at gmail.com> wrote:

> Hello,
>
> Long story short, Minor GC times jump from ~30ms to more than a second
> (and increase to about 5 seconds), and only an explicit paralell Full GC
> can whack it out of this madness. Interestingly it looks like this
> bug/feature manifests when a big ~100+ MB byte[] object gets allocated,
> thus triggering a CMS initial-sweep. (The CMS runs fine though, but the
> young gen collections take forever.)
>
> http://pastebin.com/RcBkCEEE (of course, if someone's interested I here's
> the full 50 MBs of the otherwise rather predictable log, 2.9MB compressed
> http://zomg.hu/work/wtf-gc.log.xz )
>
> We're running the stock Oracle 1.6.0_37 64bit JVM, on a 8 core new Xeon
> E3-something with plenty of RAM for the heap, with the following options:
>
> -Xmx5128M
> (-Xms5128M, though the linked gclog is without this)
> -XX:NewSize=300m
> -XX:MaxNewSize=300m
> -XX:PermSize=64m
> -XX:MaxPermSize=192m
>
> -XX:+UseParNewGC
> -XX:ParallelGCThreads=2
> -XX:MaxTenuringThreshold=4
> -XX:SurvivorRatio=3
>
> -XX:+UseConcMarkSweepGC
> -XX:+UnlockDiagnosticVMOptions
> -XX:+CMSScavengeBeforeRemark
> -XX:CMSInitiatingOccupancyFraction=65
>
> -XX:+PrintGC
> -XX:+PrintGCDetails
> -XX:+PrintTenuringDistribution
> -XX:+PrintGCDateStamps
> -XX:PrintFLSStatistics=1
> -Xloggc:/logs/gc.log
> -verbose:gc
>
> Has anyone experienced similar issues?
>
> Thanks for your time,
> Pas
>
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