The thread dump is a well-known feature of the Java Virtual Machine. It is a snapshot of the JVM that helps the WebLogic administrator analyze which Java method the Java threads were executing in at the exact moment the snapshot was taken. As in the rest of the book, the JVM used in this recipe is Oracle JRockit JVM.
In a hypothetic scenario, the WebLogic Administrator received several e-mails from the configured WLDF alerts from the previous chapter, indicating that the QueueLength value is growing up in the PROD_Server01 Managed Server. The requests are probably piling up.
In this recipe, thread dumps of PROD_Server01 will be taken to analyze the problematic scenario.
The thread dump can be taken from the Administration Console from the shell using the jrcmd command-line tool or from the JRockit Mission Control.