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.
For more information about these options, see Java Command Line Reference at http://docs.oracle.com/javase/8/docs/technotes/tools/solaris/java.html (Solaris, Linux)
http://docs.oracle.com/javase/8/docs/technotes/tools/windows/java.html (Windows)
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Note: You should use |
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 commad 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. For more information about using the jcmd command, see the jcmd documentation at:
http://docs.oracle.com/javase/8/docs/technotes/tools/windows/jcmd.html
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.
Table A-1 JFR.start
| 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.
