RE: Memory GC

> From: Eric K
> 
> I am trying to figure out why JVM full GC is occurring so 
> often in my OpenJMS Server.
> I am using version 0.7.7-alpha-1. 
> So I ended up starting an empty/clean 0.7.7-alpha-1 server 
> straight from the .tar and am see a Full JVM GC every 60 
> seconds.  There is absolutely NO activity using this server, 
> so it is not the JVM thinking it needs to 
> GC.   I have tried to change GarbageCollectionConfiguration 
> attributes 
> in the openjms.xml, but this does not change the behavior I 
> am seeing of every 60 seconds.  As extra verification I added 
> a command line switch to the JVM to disable explicit GC and 
> the behavior stopped, so it is something inside OpenJMS which 
> is explicitly calling gc().
> 
> Why is this happening? 
> Why does OpenJMS need to garabage collect so often? or for 
> that matter, Why does OpenJMS need to call JVM gc() at all?

OpenJMS doesn't invoke the garbage collector explicitly.
However, there is a JVM thread named "GC Daemon" which periodially
does invoke System.gc() - this is probably what you are seeing.
In JDK 1.3.1, the "GC Daemon" thread is an instance of sun.misc.GC$Daemon

-Tim




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