Configuring class preloading

Class preloading affects how quickly a WebSphere Application Server process starts.

 

Overview

The first time a WebSphere Application Server process starts up, the name of each class loaded and the name of the JAR file containing the class are written to a preload file. Subsequent startups of the process use the preload file to start the process more quickly.

No configuring of class preloading is necessary.

However, an administrator can disable or enable preloading explicitly. By default, class preloading is enabled for WebSphere Application Server processes. To change the configuration for class preloading, an administrator sets new values for system properties.

• Disable class preloading.Set the JVM system property ibm.websphere.preload.classes to false.

  1. In the administrative console, click Servers > Application Servers > server > Process Definition > Java Virtual Machine to access the Java Virtual Machine page.

  2. On the Java Virtual Machine page, specify -Dibm.websphere.preload.classes=false for Generic JVM arguments.

  3. Click OK.

  4. Click Save to save your administrative configuration.

  5. Stop the application server and then restart the appserver.

• Enable class preloading again.If you disabled class preloading, you can re-enable it by doing either of the following:

  • Remove the JVM system property created to disable class preloading. On the Java Virtual Machine page, clear the value for Generic JVM arguments.

  • Set the JVM system property to true. On the Java Virtual Machine page, specify -Dibm.websphere.preload.classes=true for Generic JVM arguments.

• Regenerate a class preload file.Delete the .preload file for the WebSphere Application Server process. When the process next starts up, a new class preload file is generated for the process.

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Class loaders

Class loading
    

 

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