Note:
Java Flight Recorder requires a commercial license for use in production. To learn more about commercial features and how to enable them please visithttp://www.oracle.com/technetwork/java/javaseproducts/.This appendix serves as a basic reference to the commands you can use with Java Flight Recorder. It contains the following sections:
When you launch your Java application with the java command, you can specify options to enable Java Flight Recorder, configure its settings, and start a recording. The following command-line options are specific to Java Flight Recorder:
-XX:+|-FlightRecorder
-XX:FlightRecorderOptions
-XX:StartFlightRecording
These command-line options are available only in the commercial license of the JDK. To use them, you have to also specify the -XX:+UnlockCommercialFeatures option.
Note:
You should use-XX options only if you have a thorough understanding of your system. If you use these commands improperly, you might affect the stability or performance of your system. -XX options are experimental, and they are subject to change at any time.This is a description of the diagnostic commands available to control Java Flight Recorder and the parameters available for each command. This information is also available by running the jcmd command with the process identifier specified, followed by the help parameter and the command name. For example, to get help information for the JFR.start command on a running JVM process with the identifier 5361, run the following:
jcmd 5361 help JFR.start
To get a full list of diagnostic commands available to the JVM, do not specify the name of the command.
The diagnostic commands associated with Java Flight Recorder are:
The JFR.start diagnostic command starts a flight recording. Table A-1 lists the parameters you can use with this command.
| Parameter | Description | Type of value | Default |
|---|---|---|---|
|
name |
Name of recording |
String |
|
|
settings |
Server-side template |
String |
|
|
defaultrecording |
Starts default recording |
Boolean |
False |
|
delay |
Delay start of recording |
Time |
0s |
|
duration |
Duration of recording |
Time |
0s (means "forever") |
|
filename |
Resulting recording filename |
String |
|
|
compress |
GZip compress the resulting recording file |
Boolean |
False |
|
maxage |
Maximum age of buffer data |
Time |
0s (means "no age limit") |
|
maxsize |
Maximum size of buffers in bytes |
Long |
0 (means "no max size") |
The JFR.check command shows information about running recordings. Table A-2 lists the parameters you can use with this command.
The JFR.stop diagnostic command stops running flight recordings. Table A-3 lists the parameters you can use with this command.
The JFR.dump diagnostic command stops running flight recordings. Table A-4 lists the parameters you can use with this command.