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Open Mic Replay: OutOfMemory(OOM) Issues in WebSphere Application Server



This session gives you a chance to ask questions on how to troubleshoot OOM issues in WebSphere Application Server. Topics include how to identify native and Java heap OOM, documentation to collect, analyzing data using different tools, best practices and recommendations on common issues.


Open Mic sessions are conducted in a question and answer format. The table below provides a time index (minutes:seconds) to the recording and describes the questions or topics discussed. You can fast forward to any question using the time index, a table containing the panel of experts is also included.

To play or download the audio of this Open Mic session, see the Audio Section of this document.

See the Related Information Section of this document for a list of documents referenced during the presentation.

Open Mic session
21 April 2010 - 11:00 a.m. - 12:00 p.m. EDT

TimeQuestions asked
00:00General introduction
02:38Technical introduction
04:03I'm seeing OOM errors in the WebSphere Application Server logs, where do I start? How do I determine if the OOM errors are due to Java heap exhaustion or native memory exhaustion?
07:11Now that I have identified the type of OOM condition, what documentation should I collect?
11:25How do I debug Java heap exhaustion issues and what tools should I use?
14:29How do I debug native memory exhaustion issues and what tools should I use?
17:31What are some of the potential memory suspects in WebSphere env I should be aware of, when dealing with Java heap and native memory issues?
21:02We have had success turning off AIO on AIX and observed no performance issues. What types of performance issues should we be looking for?
22:53I am developing a solution for monitoring WebSphere Application Servers. I use an AdminClient program to monitor for things like WebContainer hung threads, DataSource waiting threads, etc. Is there any way to detect if there has been an OutOfMemory Exception thrown. I realize a script could check for heap dumps or check native_stderr.log but I'm looking for something that can be checked from a client program using something like the JMX/PMI interface.
24:42Is there any rules or recommendations as to what is the minimum amount we should add to the heap size to ensure we have sufficient memory in the box for the application server during the planning phrase?
29:45In the WAS console, is it a best practice to have the initial and maximum heap size not within those boxes but within those generic JVM arguments?
33:45What is the typical session sizes out there?
34:51I am reading a white paper on a new enhanced feature in Java 6 where a script can be run when the heap is full - do you know what script this is?
42:31Can proper setting of caching size and emulated session count reduce out-of-memory issues? If yes, what parameters should we take into considerations?
44:28How do you relate the native memory to the physical memory, and if you have enough physical memory, what is the limit? Also, if you remove the no-class GC, wouldn't you suffer performance, and what are the pros/cons of using this switch?
46:13On the physical version of native issue, if you have enough physical memory, can you go beyond 1.5GB?
49:38Can you explain the difference between heap memory, native memory and server physical memory?
50:40Closing remarks
51:34End of Call

Panel of Experts:
Giri ParamkushamWebSphere Application Server Support Engineer
James FoxWebSphere Application Server Support Engineer
Jinwoo HwangWebSphere Application Server Support Engineer
Thomas IretonWebSphere Application Server Support Engineer


Click on Download Audio to play the recording of this 51 minutes conference call (6.0MB - MP3 format). Right-click and select Save As to store the file on your local computer for later playback. Remember that you can fast forward to any question using the time index.

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Document Information

Modified date:
17 June 2018