Explanation: A: You can enable JFR at runtime to take JRA recordings from the JRockit Management Console. You also have the option of turning off the JFR and recordings at the JRockit JVM level from the java command line using:
$ java -XX:-FlightRecorder
B:
* In most environments, there is little performance impact when the Diagnostic Volume is set to Low and the most performance impact if Diagnostic Volume is set to High. The volume of diagnostic data produced by WebLogic Server needs to be weighed against potential performance loss.
*WLDF provides the Diagnostic Volume attribute to set the amount of code coverage that is enabled and the amount of data provided in the events that are generated for the covered code
The following code example sets the volume to Medium:
connect()
edit()
startEdit()
cd("Servers/myserver")
cd("ServerDiagnosticConfig")
cd("myserver")
cmo.setWLDFDiagnosticVolume("Medium")
save()
activate()
D: Integrated with the WebLogic Diagnostic Image and Watch and Notification
system
• Enables capture based on system state, event – capture during event; no need to replicate
• Watch for stuck thread count, heap size increase, available memory, etc.
• Set up notifications: capture WLDF image
• Diagnostic image capture spurs JFR file generation; JFR file included in diagnostic image
• Includes full JFR data from all event generators
Note:
* WebLogic Diagnostic Framework (WLDF) provides specific integration points with JRockit Mission Control Flight Recorder. WebLogic Server events are propagated to the Flight Recorder for inclusion in a common data set for runtime or post-incident analysis.