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

[Pas]

Hello!

I assume promotion volume is the size of the last age group in the tenuring
distribution, in my case the age 4 group. From the start of this "more than
1 second minor GC" regime, promotion volume hasn't changed, usually less
than one megabyte, and to the end of the log it stays below 12MB. (~1100
ParNew GCs, only 172 above one MB.)

Thanks,
Pas

On Sun, Jan 27, 2013 at 9:00 PM, Srinivas Ramakrishna <ysr1729 at gmail.com>wrote:

> 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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>>
>>
>
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