Enabling traces for debugging class loader issues in Websphere Application Server 6.1

Enabling Class loader traces:

 Use the following steps to collect a class loader trace for WebSphere Application server Version 6.1:-

1. Log on to the administrative console.

2. In the left navigational panel, expand Troubleshooting. Click Logs and Trace.

3. Select the application server to be traced, and then on the next page click the Diagnostic Trace link.

4. Select the Configuration tab.

5. Select the Enable Log property.

6. Under Trace Output, select the File radio button, and specify the file name. Also Increase the Maximum file size to 100 MB, and increase the Maximum number of historical files to 10.

7. Select Basic (Compatible) Trace Output Format.

8. Navigate to Logging and Tracing > application_server > Change Log Detail Levels.

9. Under the Configuration tab, specify the trace string suggested.

10.Click Apply and OK. Save your configuration. Select the Synchronize changes with Nodes option if you are using a distributed environment.

 

 

Enabling JVM class loader and bootstrap traces:

To enable the Java Virtual Machine (JVM) class loader and bootstrap traces for Version 6.1, do the following:

1. From the administrative console, select Servers > Application servers, and select the problem server.

2. On the right side, under Server Infrastructure, expand Java and Process Management.

3. Click Process Definition.

4. Under Additional Properties, select Java Virtual Machine.

5. Enable the following Properties by selecting the check boxes located on the left of the property.

– Verbose class loading

– Verbose JNI

6. Click Apply.

7. On right side under Additional Properties, click Custom Properties.

8. Click New.

9. Enter the following custom properties:

– Name: ws.ext.debug

– Value: true

10.Click Apply and OK. Save your configuration. Select the Synchronize

changes with Nodes option if you are using a distributed environment.

 

 

Using the Class Loader Viewer:

 

The Class Loader Viewer in the administrative console can be used to determine how a class is loaded by the class loaders in the WebSphere Application Server.

Enable the Class Loader Viewer service:

If the Class Loader Viewer service is not enabled, the Class Loader Viewer only displays the hierarchy of class loaders and their classpaths, but not the classes actually loaded by each of the class loaders. This also means that the search capability of the Class Loader Viewer is lost.

 To enable the Class Loader Viewer Service, select Servers Application Servers server_name, and then click the Class Loader Viewer Service under the Additional Properties link.

Next, select Enable service at server startup.

Restart the application server for the setting to take effect.

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