1 Command-Line Options

When you use the java command to start a Java application, you can specify options to enable Java Flight Recorder, configure its settings, and start a recording.

The following command-line options for the java command are specific to Java Flight Recorder:

  • -XX:+|-FlightRecorder: Enables Java Flight Recorder (not required for JDK 8u40 and later)

  • -XX:FlightRecorderOptions: Sets the parameters for Java Flight Recorder

  • -XX:StartFlightRecording: Starts a recording with the provided parameters, or with the default values

The command-line options for Java Flight Recorder are described in the java chapter of the Java Platform, Standard Edition Tools Reference. These options are available only in the commercially licensed JDK from Oracle. To use these options, you must unlock the commercial features as described in the next section.

Unlocking Commercial Features

Use one of the following methods to access for Java Flight Recorder and related options:

  • Specify the -XX:+UnlockCommercialFeatures option when you start your application with the java command.

  • Use the VM.unlock_commercial_features parameter for the jcmd utility to unlock commercial features after the application is running.

Example 1-1 Unlock Commercial Features When Starting an Application

The following java command unlocks commercial features for an application named MyApp and starts a recording:

java -XX:+UnlockCommercialFeatures -XX:StartFlightRecording MyApp

Example 1-2 Unlock Commercial Features for a Running Application

The following jcmd command unlocks commercial features for a Java process with the process ID 1968:

jcmd 1968 VM.unlock_commercial_features