Memory Issues

[Day, Chuck]

We’re running into memory issues in our WebLogic 10.3 Clusters running Grails 1.3.5.   We have multiple Grails apps deployed to the same cluster and, after running for a while, the CPU gets consumed with garbage collection such that the applications slow down significantly.  We’ve been specifying 512 MB per parameter (e.g. Min, Max, Perm) in the WebLogic startup scripts per managed server.  Wondering if we are trying to run too many Grails applications in the same JVM. 

 

Does anyone have suggestions about environment configurations to be shared such as the parameter settings or the number of Grails applications deployed per JVM?  I couldn’t find anything pertinent on the GUM postings since 2007.

 

Thanks for any help.

 

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[Dan Tanner]

512 can be a little small for many of the grails apps I've seen.  Have you tried increasing the memory for one or all of the nodes as an experiment?  e.g. Here's the JAVA_OPTS settings I use for one of my environments (this is tomcat, but it should be similar)

-server -Xms1024M -Xmx1024M -XX:MaxPermSize=128m

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[Michael Nadel]

The sure-fire approach is to profile your app. It's important to understand the app's memory characteristics. You may, for example, find that you need to tweak the generational ratios.

Here's a great resource:

http://www.oracle.com/technetwork/java/javase/gc-tuning-6-140523.html

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[Jeff Beck]

You may also have decent luck with changing the GC you are using. Depending on how your application is dealing with memory you can get better performance out of the different collectors. I had good luck with the concurrent mark sweep collector. I haven't tried the G1 collector yet that came with jdk7 u4. I would check both of those out but also move down your perm to only slightly above what you need you can give your self more heap then.

Jeff