Specifying trace options

The preferred way to control trace is through trace options that you specify by using the -Xtrace option on the launcher command line, or by using the IBM_JAVA_OPTIONS environment variable.

Some trace options have the form <name> and others are of the form <name>=<value>, where <name> is case-sensitive. Except where stated, <value> is not case-sensitive; the exceptions to this rule are file names on some platforms, class names, and method names.

If an option value contains commas, it must be enclosed in braces. For example:

methods={java/lang/*,com/ibm/*}

Note: The requirement to use braces applies only to options specified on the command line. You do not need to use braces for options specified in a properties file.

The syntax for specifying trace options depends on the launcher. Usually, it is:

java -Xtrace:<name>,<another_name>=<value> HelloWorld

To switch off all tracepoints, use this option:

java -Xtrace:none=all

If you specify other tracepoints without specifying -Xtrace:none, the tracepoints are added to the default set.

When you use the IBM_JAVA_OPTIONS environment variable, use this syntax:

set IBM_JAVA_OPTIONS=-Xtrace:<name>,<another_name>=<value>

export IBM_JAVA_OPTIONS=-Xtrace:<name>,<another_name>=<value>

If you use UNIX-style shells, note that unwanted shell expansion might occur because of the characters used in the trace options. To avoid unpredictable results, enclose this command-line option in quotation marks. For example:

java "-Xtrace:<name>,<another_name>=<value>" HelloWorld

For more information, see the manual for your shell.