Troubleshooting WebLogic Server 12c - Oracle WebLogic Server 12c Advanced Administration - page 193

Enabling the verbose GC with jrcmd
The verbose GC can be enabled without restarting the JVM using the jrcmd
command-line tool.
1. Find the <PID> value of the PROD_Server01 Managed Server process:
[wls@prod01]$ ps aux | grep PROD_Server01 | grep -v grep | awk
'{print $2} '
<PID>
2. Issue a jrcmd command using <PID> as an argument:
[wls@prod01]$ /oracle/jvm/bin/jrcmd <PID> verbosity set=gc,memory
See also
F Changing log levels to debug
F Including the time taken in access.log
Taking thread dumps
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 topic, 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.
Getting ready
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.