Java Platform, Standard Edition Java Flight Recorder Runtime Guide
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A Command Reference

This appendix serves as a basic reference to the commands you can use with the Java Flight Recorder. It contains these sections:

A.1 Command-Line Options

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:+UnlickCommercialFeatures option.

For more information about these options, see Java Command Line Reference at http://docs.oracle.com/javase/7/docs/technotes/tools/solaris/java.html (Solaris, Linux)
http://docs.oracle.com/javase/7/docs/technotes/tools/windows/java.html (Windows)


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 experimantal, and they are subject to change at any time.


A.2 Diagnostic Command Reference

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 typing jcmd <pid> help <command>. The diagnostic commands associated with Java Flight Recorder are:

For more information about using the jcmd command, see the jcmd documentation at:

http://docs.oracle.com/javase/7/docs/technotes/tools/windows/jcmd.html

A.2.1 JFR.start

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")


A.2.2 JFR.check

The JFR.check command shows information about running recordings. Table A-2 lists the parameters you can use with this command.

Table A-2 JFR.check

Parameter Description Type of value Default

name

Recording name

String


recording

Recording id

Long

1

verbose

Print verbose data

Boolean

False


A.2.3 JFR.stop

The JFR.stop diagnostic command stops running flight recordings. Table A-3 lists the parameters you can use with this command.

Table A-3 JFR.stop

Parameter Description Type of value Default

name

Recording name

String


recording

Recording id

Long

1

discard

Discards the recording data

Boolean


copy_to_file

Copy recording data to file

String


compress_copy

GZip compress "copy_to_file" destination

Boolean

False


A.2.4 JFR.dump

The JFR.dump diagnostic command stops running flight recordings. Table A-4 lists the parameters you can use with this command.

Table A-4 JFR.dump

Parameter Description Type of value Default

name

Recording name

String


recording

Recording id

Long

1

copy_to_file

Copy recording data to file

String


compress_copy

GZip compress "copy_to_file" destination

Boolean

False


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