WAS v8.5 > Tune performance > Obtain advice from the advisors > Use the Performance and Diagnostic Advisor

Enable automated heap dump generation

Use this task to enable automated heap dump generation. This function is not supported when using a Sun 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.

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 WAS for several minutes.

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.

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.

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 we determine that enough memory is leaked, so that we can compare the heap dumps to find the source of the leak.

To help you analyze memory leak problems when memory leak detection occurs, some automated heap dump generation support is available.

To enable automated heap dump generation support, perform the following steps in the dmgr console:

1. Click Servers > Application servers in the dmgr 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

The automated heap dump generation support is enabled.

To preserve disk space, the Performance and Diagnostic Advisor does not take heap dumps if more than 10 heap dumps already exist in the WAS 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.

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.

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

IBM recommends using the HPEL log and trace infrastructure. With HPEL, one views logs using the LogViewer command-line tool in PROFILE/bin.

Subtopics

• Generate heap dumps manually
  Use this task to generate heap dumps manually. This function is not supported on when using a Sun JVM which includes WAS running on HP-UX and Solaris operating systems.
• Locating and analyzing heap dumps
  Use this task to locate and analyze heap dumps.
• Generate heap dumps manually
  Use this task to generate heap dumps manually. This function is not supported on when using a Sun JVM which includes WAS running on HP-UX and Solaris operating systems.
• Locating and analyzing heap dumps
  Use this task to locate and analyze heap dumps.

Related

Start the lightweight memory leak detection
Troubleshoot applications with HPEL

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