[jboss-user] [Performance Tuning] - JVM pauses periodically

jamesd256 do-not-reply at jboss.com
Thu Aug 21 09:49:03 EDT 2008


We are having trouble with our production application server; the JVM seems to pause from time to time.  

This is apparent both in lack of responsiveness, and gaps in the logs.  Normally we have tens of log lines per second, but we see gaps where nothing is logged for anything from 4-30 seconds.

The server is under constant load, and averages about 150 threads, peaking at about 300.

It's running on 32 bit Ubuntu Server using the Sun 1.6.0-b105 JVM.

The jvm is started with the following:

JAVA_OPTS="-server -Xms2048m -Xmx2048m -XX:PermSize=128m -XX:MaxPermSize=128m 

We have a tool which graphs the memory pools of the JVM, and I can see that survivor space and eden space are running at high percentages, while heap usage stays around 20%, peaking at up to 70%.

At present the JVM uptime is 203035600 and the following GC figures are as follows.

PS Scavenge:  CollectionCount (9364)                 CollectionTime (321892)
PS MarkSweep:  CollectionCount (57)                   CollectionTime (67529)

>From my understanding of these figures, the throughput of the JVM seems ok to me, and doesn't seem to account for the pauses.

I occasionally take a thread dump and find deadlocked threads, but normally there are none.

My questions are; what should I be monitoring?  Can I tweak the JAVA_OPTS to change some (ratio?) settings?

I've tried to find the right forum for this, so sorry if this isn't it.  If you know a better place to ask, I'd be grateful.

Thanks in advance,


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