Configuring and Running JRockit

This section describes how to use JRockit's command line options. JRockit supports all the standard Java command line options plus numerous extended options.

This section includes information on the following subjects:

• Setting Up JRockit by Using Standard Command Line Options
• Setting Standard Output Options
• Changing JRockit Behavior by Using -X Options
• Configuring Garbage Collection and Thread Management by Using -X Options

Note: If JRockit behaves in some unexpected way, please consult the JRockit FAQ. If that doesn't solve your problem, please send an e-mail to [e-mail]

 

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Setting Up JRockit by Using Standard Command Line Options

The following are the standard command line options you can use with JRockit:

• -classpath <directories and zips/jars separated by : or ;>

Tells JRockit where to look for classes and resources.

Use a semicolon to separate entries on Windows systems and a colon on Linux. Alternately, you can use the option -cp to represent -classpath; for example:

-cp <directories and zips/jars separated by : or ;>

• -D<name>[=<value>]

Tells JRockit to set a Java system property. These can be read by a Java program, using the methods in java.lang.System.

 

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Setting Standard Output Options

The following options determine if the system will provide messages to the operator and what the form and content of those messages should be.

• -version

Tells JRockit to display its product version number and then exit.

• -showversion

Tells JRockit to display its product version number and then continue.

• -verbose[:<components separated by ,>]

Tells JRockit to display verbose output. This option is used mainly for debugging purposes and causes a lot of output to the console. Supported components are memory, load and codegen. If no component is given, JRockit will display verbose information on everything.

• -help

Tells JRockit to display a short help message.

• -X

Tells JRockit to display a short help message on the extended options.

 

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Changing JRockit Behavior by Using -X Options

The -X command line options are used to change the behavior of JRockit to better suit the needs of different Java applications.

Warning: -X options are non-standard and are subject to change at any time.

• -Xnoopt

Tells JRockit not to optimize code.

• -Xverify

Tells JRockit to do complete bytecode verification.

 

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Preventing JRockit from Initiating Shutdown After Receiving a Logoff Event

-Xnohup

If the JRockit is run as a service (for example, the servlet engine for a web server), it can receive CTRL_LOGOFF_EVENT or SIGHUP but should not initiate shutdown, since the operating system will not actually terminate the process. To avoid possible interference such as this, use the -Xnohup command-line option. When this option is used with JRockit, the JVM does not watch for or process CTRL_LOGOFF_EVENT or SIGHUP events.

If you specify -Xnohup, be aware of the following:

• Ctrl-Break thread dumps are not available.
• User code is responsible for causing shutdown hooks to run; for example by calling System.exit() when JRockit is to be terminated.

 

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Configuring Garbage Collection and Thread Management by Using -X Options

Additional -X options, specific to garbage collection and threading, are described in Configuring the JRockit Memory Management System and Configuring the JRockit Thread System.