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
About this task
![[IBM i]](../images/iseries.gif)
- 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.
The Heap Analyzer tool is a component of the iDoctor for IBM i suite of performance monitoring tools
Use the heap monitor feature to monitor the JVM heap size of a WebSphere Application Server profile in comparison to pool
size.
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 you determine that enough
memory is leaked, so that you 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 administrative console:
![[AIX Solaris HP-UX Linux Windows]](../images/dist.gif)
![[z/OS]](../images/ngzos.gif)
Procedure
- Click Servers > Application servers in the administrative console navigation tree.
- Click server_name >效能和診斷顧問 Configuration.
- Click the Runtime tab.
- Select the Enable automatic heap dump collection check box.
- Click OK.
![[AIX Solaris HP-UX Linux Windows]](../images/dist.gif)
![[z/OS]](../images/ngzos.gif)
Results
Important: To preserve disk space, the 效能和診斷顧問 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.
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.
![[AIX Solaris HP-UX Linux Windows]](../images/dist.gif)
![[z/OS]](../images/ngzos.gif)