Any pointers for tuning 1.5.0_22 for a webapp with a large tenured gen?

Jon Masamitsu jon.masamitsu at oracle.com
Mon Jul 12 09:22:51 PDT 2010


Justin,

This alias is mainly for Openjdk issues and that would currently be
jdk7.  For help with tuning jdk5, check with your Sun/Oracle
support contacts.  They should be able to give you good tuning
advice on jdk5.

Jon

On 7/12/10 8:29 AM, Justin Ellison wrote:
> Hello everyone,
>
> We've recently upgraded our Weblogic webapp to Weblogic 9.2.1 which 
> also involved upgrading from jdk 1.4.2 to 1.5.0_22.  Java 6 isn't an 
> option with Weblogic 9.2, and the upgrade to Weblogic 10 isn't until 
> next year, so Java 6 is not an option for me at this point in time.
>
> I had the 1.4.2 tuned to the extreme:
> JAVA_ARGS=-Xms2816m -Xmx2816m -XX:NewSize=384m -XX:MaxNewSize=384m -XX:CompileThreshold=3000 -Djava.net.setSoTimeout=20000 \
> -XX:LargePageSizeInBytes=4m -XX:+UseMPSS -Xss128k -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+CMSParallelRemarkEnabled \
>
> -Xnoclassgc -XX:ParallelGCThreads=4 -XX:MaxTenuringThreshold=8 -XX:SurvivorRatio=6 -XX:+UseCMSCompactAtFullCollection -Xloggc:gc.out \
> -verbose:gc -XX:+PrintGCTimeStamps -XX:+PrintGCDetails -XX:MaxPermSize=92m
> With our upgrade, the ergonomics of the application changed some, so I 
> just specified Xmx and Xms at 3GB, and let it run to see what 
> happened.  Remarkably, things were actually pretty good - minor GC's 
> are faster, and major GC's only occur about once or twice an hour.  
> However, those major GC's are taking from 12-20seconds, which I can't 
> let our website users endure.
>
> Before I go down the road of tuning things, does anyone have any tips 
> for me?  I can afford at most 2 or 3 seconds of pause time at once, 
> and would prefer to keep it under 2 seconds if possible.  I need the 
> 2GB of tenured to be able to cache all the objects that I need to 
> ensure good site performance.
>
> The ergonomics look kinda cool, but I'm wondering if that large of 
> tenured generation + my low pause requirement is just too much to ask 
> from the throughput collector.  Am I destined to go back to hand 
> tweaking the CMS collector?
>
> Justin
>
>
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>    

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