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

[IBM i]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.

[IBM i]The Heap Analyzer tool is a component of the iDoctor for IBM i suite of performance monitoring tools

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

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

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

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

Procedure

  1. Click Servers > Application servers in the administrative console navigation tree.
  2. Click server_name >效能和診斷顧問 Configuration.
  3. Click the Runtime tab.
  4. Select the Enable automatic heap dump collection check box.
  5. Click OK.
[AIX Solaris HP-UX Linux Windows][z/OS]

Results

The automated heap dump generation support is enabled.

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

[AIX Solaris HP-UX Linux 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.

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

What to do next

You can monitor any notifications of memory leaks by checking the SystemOut.log file or Runtime Messages. For more information, see the Viewing the 效能和診斷顧問 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.
Note: 這個主題參照一或多個應用程式伺服器日誌檔。 此外,在分散式和 IBM i 系統上,另外也建議您可以配置伺服器來使用「高效能可延伸記載 (HPEL)」日誌和追蹤基礎架構,而不使用 SystemOut.logSystemErr.log, trace.logactivity.log 檔案。HPEL 與原生 z/OS® 記載機能也可以一起使用。如果您使用 HPEL,則可以從伺服器設定檔 bin 目錄,利用 LogViewer 指令行工具來存取您所有的日誌和追蹤資訊。請參閱有關利用 HPEL 疑難排解應用程式的資訊,以取得更多使用 HPEL 的相關資訊。

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時間戳記圖示 前次更新: July 9, 2016 11:16
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