WebSphere Application Server Version 6.1 Feature Pack for Web Services
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Enabling automated heap dump generation

Use this task to enable automated heap dump generation. This function is not supported when using a Sun Java virtual machine (JVM) which includes WebSphere Application Server running on HP-UX and Solaris operating systems. You need to research taking heap dumps on Sun JVMs or call IBM Support.

Before you begin

Although heap dumps are only generated in response to a detected memory leak, you must understand that generating heap dumps can have a severe performance impact on WebSphere Application Server for several minutes.

About this task

[i5/OS] To help you analyze memory leak problems when memory leak detection occurs, use the Heap Analysis Tools for Java™. Use the Heap Analysis Tools component (also known as Heap Analyzer) to perform Java application heap analysis and object create profiling (size and identification) over time. Heap Analyzer includes information about:
  • Java virtual machine (JVM) heap growth or size
  • The objects being created that include type of object, count and object size, object heap size
  • The application "Heap Footprint" for memory sizing and performance considerations
  • Includes a call stack for every snapshot when running in profile mode so objects created can be correlated to functions in the application.

[i5/OS] The Heap Analyzer tool is a component of the iDoctor for iSeries suite of performance monitoring tools

[i5/OS] Use the heap monitor feature to monitor the JVM heap size of a WebSphere Application Server profile in comparison to pool size.

[AIX HP-UX Linux Solaris Windows] The automated heap dump generation support, which is available only on IBM Software Development Kit and analyzes memory leak problems on AIX, Linux, and Windows operating systems.

[AIX HP-UX Linux Solaris Windows] Manually generating heap dumps at appropriate times might be difficult. To help you analyze memory leak problems when memory leak detection occurs, some automated heap dump generation support is available. This functionality is available only for IBM Software Development Kit on AIX, Linux, and Windows operating systems.

[AIX HP-UX Linux Solaris Windows] Most memory leak analysis tools perform some forms of difference evaluation on two heap dumps. Upon detection of a suspicious memory situation, two heap dumps are automatically generated at appropriate times. The general idea is to take an initial heap dump as soon as problem detection occurs. Monitor the memory usage and take another heap dump when you determine that enough memory is leaked, so that you can compare the heap dumps to find the source of the leak.

[AIX HP-UX Linux Solaris Windows] [z/OS] To help you analyze memory leak problems when memory leak detection occurs, some automated heap dump generation support is available.

[AIX HP-UX Linux Solaris Windows] [z/OS] To enable automated heap dump generation support, perform the following steps in the administrative console:

Procedure [AIX HP-UX Linux Solaris Windows] [z/OS]

  1. Click Servers > Application servers in the administrative console navigation tree.
  2. Click server_name >Performance and Diagnostic Advisor Configuration.
  3. Click the Runtime tab.
  4. Select the Enable automatic heap dump collection check box.
  5. Click OK.

Results [AIX HP-UX Linux Solaris Windows] [z/OS]

The automated heap dump generation support is enabled.

[AIX HP-UX Linux Solaris Windows] [z/OS] Important: To preserve disk space, the Performance and Diagnostic Advisor does not take heap dumps if more than 10 heap dumps already exist in the WebSphere Application Server home directory. Depending on the size of the heap and the workload on the application server, taking a heap dump might be quite expensive and might temporarily affect system performance.

[AIX HP-UX Linux Solaris Windows] [z/OS] The automatic heap dump generation process dynamically reacts to various memory conditions and generates dumps only when it is needed. When the heap memory is too low, the heap dumps cannot be taken or the heap dump generation cannot be complete.

What to do next [AIX HP-UX Linux Solaris Windows] [z/OS]

You can monitor any notifications of memory leaks by checking the SystemOut.log file or Runtime Messages. For more information, see the Viewing the Performance and Diagnostic Advisor recommendations topic. If a memory leak is detected and you want to find the heap dump, refer to the Locating and analyzing heap dumps topic.



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Last updated: Nov 25, 2008 2:35:59 AM CST
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