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All Things WebSphere

Concerns and issues relating to all versions of WebSphere Application Server

Tuesday, October 25, 2011

 

Excessive DirectByteBuffer WebSphere Application Server native allocations

Things that we recommend to customers who  are dealing java and native heap issues due to excessive DirectByteBuffer allocations.


Switching AIO to NIO
http://www-01.ibm.com/support/docview.wss?uid=swg21366862

Setting the WebSphere Application Server WebContainer to synchronous mode
http://www.ibm.com/support/docview.wss?uid=swg21317658

Introspection of  system dumps generated on an OOM with IBM Product Extensions into Memory Analyzer Tool: Run the following query
Open Query Browser → IBM Extensions → Java SE Runtime → DirectByteBuffers

Fixed size Major thread pools (WebContainer, etc.) (min=max)
http://www-01.ibm.com/support/docview.wss?uid=swg21368248

IBM Health Center has native memory monitoring
Generic JVM argument -Xhealthcenter
-Xhealthcenter:level=low to not gather profiling data
Support Assistant  -Xhealthcenter:level=headless for writing to an HCD file

Javacore memory analysis script
get_memory_use.pl
http://www.ibm.com/developerworks/aix/library/j-nativememory-aix/index.html

Enable explicit GC
If ExplicitGC has been disabled please enable it

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