WAS v8.5 > Set up the application serving environment > Administer application servers

Configure the JVM

As part of configuring an application server, you might define settings that enhance the way your operating system uses of the JVM.

The JVM is an interpretive computing engine that is responsible for running the byte codes in a compiled Java program. The JVM translates the Java byte codes into the native instructions of the host machine. The application server, being a Java process, requires a JVM to run and to support the Java applications running on it. JVM settings are part of an application server configuration.

To view and change the JVM configuration for an application server process, use the Java virtual machine page of the dmgr console or use wsadmin scripts to change the configuration.

When a child process starts, Java appends the runtime path to the LIBPATH environment variable to ensure that it is using the correct library paths. Because this implementation does not check to see if the runtime path already exists in the LIBPATH environment variable, existing entries might be duplicated. However, when the parent process restarts, all of the runtime paths that were added to the LIBPATH environment variable when child processes started are removed from the LIBPATH environment variable.

1. In the dmgr console, click Servers > Server Types > WebSphere application servers > server_name.

2. Under Server Infrastructure, click Java and process management > Process definition.

3. Select Java virtual machine.

4. Specify values for the JVM settings as needed, and click OK. For more information, see the documentation about Java virtual machine settings.

   Java 5.0 SR10 and Java 6 SR5 correct issues in which the JVM does not shut down correctly. If we have an application that depends on the previous behavior, which is not correct, we can revert to the previous behavior by adding the -XXallowvmshutdown:false argument to the Generic JVM arguments section.

5. Click Save in the messages section of the dmgr console panel to save the changes to the master configuration.

6. Restart the application server.

Example

Configure application servers for UCS Transformation Format provides an example that involves specifying a value for the Generic JVM Arguments property on the Java virtual machine page to enable UTF-8 encoding on an application server. Enabling UTF-8 allows multiple language encoding support to be used in the dmgr console.
Configure JVM sendRedirect calls to use context root provides an example that involves defining a property for the JVM.

Subtopics

• Java virtual machine settings
  Use this page to view, and change the JVM configuration settings of a process for an application server.
• Configure JVM sendRedirect calls to use context root
  If the com.ibm.websphere.sendredirect.compatibility property is not set and the application servlet code has statements such as sendRedirect("/home.html"), the web browser might display messages such as Error 404: No target servlet configured for uri: /home.html.
• Java virtual machine custom properties
  We can use the dmgr console to change the values of JVM custom properties.
• Java virtual machine settings
  Use this page to view, and change the JVM configuration settings of a process for an application server.
• Configure JVM sendRedirect calls to use context root
  If the com.ibm.websphere.sendredirect.compatibility property is not set and the application servlet code has statements such as sendRedirect("/home.html"), the web browser might display messages such as Error 404: No target servlet configured for uri: /home.html.
• Java virtual machine custom properties
  We can use the dmgr console to change the values of JVM custom properties.

Related

Get started with wsadmin scripting
Tune the IBM virtual machine for Java

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