ParallelGCThreads

[Victor Cheung]

I don't know why this didn't hit me until now.  But our server is running 2 JBoss services like so:

service jboss-app1 start
service jboss-app2 start

Therefore I'm assuming that's 2 JVMs running (I will confirm this soon with the admin), and since the young generation collector is defaulted to use the -XX:+UseParallelGC, I should set the -XX:ParallelGCThreads=4 for both of the applications given that they are both running on the same 8CPU machine.  Is this correct?

This thread (http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2008-April/000235.html) says that:

Having many more net GC worker threads than cores will often increase
GC termination times because workers with work to do will not get time on
a CPU. This can appear as either longer (or more erratic) GC pauses,
that might translate into erratic application-level response times.

Could this be a possible cause of "OutOfMemoryException GC overhead limit exceeded" errors?

victor
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