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
|04:03||I'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?|
|07:11||Now that I have identified the type of OOM condition, what documentation should I collect?|
|11:25||How do I debug Java heap exhaustion issues and what tools should I use?|
|14:29||How do I debug native memory exhaustion issues and what tools should I use?|
|17:31||What are some of the potential memory suspects in WebSphere env I should be aware of, when dealing with Java heap and native memory issues?|
|21:02||We have had success turning off AIO on AIX and observed no performance issues. What types of performance issues should we be looking for?|
|22:53||I 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.|
|24:42||Is 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?|
|29:45||In 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?|
|33:45||What is the typical session sizes out there?|
|34:51||I 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?|
|42:31||Can proper setting of caching size and emulated session count reduce out-of-memory issues? If yes, what parameters should we take into considerations?|
|44:28||How 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?|
|46:13||On the physical version of native issue, if you have enough physical memory, can you go beyond 1.5GB?|
|49:38||Can you explain the difference between heap memory, native memory and server physical memory?|
|51:34||End of Call|
Panel of Experts:
|Giri Paramkusham||WebSphere Application Server Support Engineer|
|James Fox||WebSphere Application Server Support Engineer|
|Jinwoo Hwang||WebSphere Application Server Support Engineer|
|Thomas Ireton||WebSphere Application Server Support Engineer|
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17 June 2018