GC performance and Class Loading/Unloading

[Rob3]

We have EP 6.0, SP11 on Solaris with JDK 1.4.8_02. We are running Web Dynpro version of MSS/ESS and Adobe Document Services. This is a Java stack only Web AS.

We are experiencing very uneven performance on the Portal. Usually, when the Portal grinds to a halt, the server log shows GC entries or Class unloading entries for the entire time the Portal stops working.

I am thinking about setting the GC parameters to the same size to try and eliminate sudden GC interruptions. Also, what parameter can I set to allow as many classes to be loaded at startup and stay in memory for as long as possible?

Thanks,

Rob Bartlett

[swapan_saha · Accepted solution]

Hi Rob,

Please check your JVM memory setting based on SAP Note 716604. You will see unloading classes when we do not tune Permanent Space (by PermSize) appropriately and make sure "NewSize", "MaxNewSize" are correctly specified with the corresponding "mx" and "ms" parameters.

Thanks,

Swapan Saha

[Former Member · Accepted solution]

Hi Robert

Also, if the host running the WebAS is a multi processor machine, then setting the flags

-XX:+UseConcMarkSweepGC and

-XX:+UseParNewGC

will help reduce the pause time during the GC collection in old generation and the young genereation respectively, as the GC will happen using multiple threads

I can suggest you to check if the GC performs a minor collection or major collection by enabling the flags

-verbose:gc

-XX:+PrintGCTimeStamps

-XX:+PrintGCDetails. Based on this, try to tune the young or old generation.

Regards

Madhu