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java 1.4.2 garbage collector performance

 
John Turnbull
Occasional Contributor

java 1.4.2 garbage collector performance

Hi,
we're using java version "1.4.2"
Java(TM) 2 Runtime Environment, Standard Edition
Fast VM (build 1.4.2-4.p2, native threads, mixed mode, 05/10/2005-02:43)
on OSF1 V5.1 2650 alpha, to run a weblogic 8.1 server.

We're having a problem where the server times out when the garbage collection phase takes 30 seconds or more. I've raised this with BEA but they're tending to blame the jvm for this and aren't too clued up on this implementation.

So the question is, should the garbage collection take this long, and should a client hang whilst it's going on?

I've been doing some experiments, and if I have minimal apps running, no heap specified, the server runs happily with 100Mb of heap and does the collecting c. 0.1 seconds. If I increase the heap size to c. 500Mb, the garbage collection takes 10-30 seconds (I increase the heap either explicitly with -Xms java flag or grow it by grabbing memory in other apps - the net effect is the same).

The machine has 1Gb of memory, we're trying to run 2 weblogic servers on it. No java flags specified other than -Xverbosegc

TIA,
John