Generating heap dumps manually

Use this task to generate heap dumps manually. This function is not supported on when using a Sun Java virtual machine (JVM) which includes WebSphere Application Server running on HP-UX and Solaris operating systems.

 

Before you begin

Although heap dumps are generated only in response to a detected memory leak, understand that generating heap dumps can have a severe performance impact on WebSphere Application Server for several minutes. When generating multiple heap dumps manually for memory leak analysis, make sure that significant objects are leaked in between the two heap dumps. This approach enables problem determination tools to identify the source of the memory leak.

 

About this task

You might want to manually generate heap dumps for the analysis of memory leaks. On a Java virtual machines (JVM) in WebSphere Application Server, we cannot enable automated heap dump generation. You might want to designate certain times to take heap dumps because of the overhead involved. On JVM in WebSphere Application Server, we can manually produce heap dumps by using the generateHeapDump operation on WAS managed beans (MBeans) that are special Java beans.

The WebSphere Application Server wsadmin tool provides the ability to run scripts. Use the wsadmin tool to manage a WAS installation, as well as configuration, application deployment, and server runtime operations. WebSphere Application Server supports the Jacl and Jython scripting languages only. To learn more about the wsadmin tool, see the Starting the wsadmin scripting client topic.

 

Procedure

  1. Start the wsadmin scripting client. You have several options to run scripting commands, ranging from running them interactively to running them in a profile.

  2. Invoke the generateHeapDump operation on a JVM MBean, for example,

    • Finding JVM objectName 

      <wsadmin> set objectName [$AdminControl queryNames 
WebSphere:type=JVM,process=<servername>,node=<nodename>,*]

    • Invoking the generateHeapDump operation on JVM MBean 

      <wsadmin> $AdminControl invoke $objectName generateHeapDump

      where,

      $ is a Jacl operator for substituting a variable name with its value
      invoke is the command
      generateHeapDump is the operation you are invoking
      <servername> is the name of the server on which you want to generate a heap dump
      <nodename> is the node to which <servername> belongs

 

What to do next

After running the wsadmin command, the file name of the heap dump is returned. For more information on finding heap dumps, refer to the Locating and analyzing heap dumps topic. When you have a couple of heap dumps, use a number of memory leak problem determination tools to analyze your problem.

Related tasks
Enabling automated heap dump generation


Related information


Locating and analyzing heap dumps