IBM User Guide for Java V7 on Windows > Troubleshooting and support > Using diagnostic tools > Tracing Java applications and the JVM > Controlling the trace > Detailed descriptions of trace options

properties[=<filename>]

You can use properties files to control trace. A properties file saves typing and, over time, causes a library of these files to be created. Each file is tailored to solving problems in a particular area.

This trace option allows you to specify in a file any of the other trace options, thereby reducing the length of the invocation command-line. The format of the file is a flat ASCII file that contains trace options. If <filename> is not specified, a default name of IBMTRACE.properties is searched for in the current directory. Nesting is not supported; that is, the file cannot contain a properties option. If any error is found when the file is accessed, JVM initialization fails with an explanatory error message and return code. All the options that are in the file are processed in the sequence in which they are stored in the file, before the next option that is obtained through the normal mechanism is processed. Therefore, a command-line property always overrides a property that is in the file.

An existing restriction means that you cannot leave properties that have the form <name>=<value> to default if they are specified in the property file; that is, you must specify a value, for example maximal=all.

Another restriction means that properties files are sensitive to white space. Do not add white space before, after, or within the trace options.

You can make comments as follows:

// This is a comment. Note that it starts in column 1

Examples

• Use IBMTRACE.properties in the current directory:

  -Xtrace:properties 

  • Use trace.prop in the current directory:

    -Xtrace:properties=trace.prop

  • Use c:\trc\gc\trace.props:

    -Xtrace:properties=c:\trc\gc\trace.props 

Here is an example property file:

minimal=all 
// maximal=j9mm 
maximal=j9shr 
buffers=20k 
output=c:\traces\classloader.trc 
print=tpnid(j9vm.23-25)

Parent: Detailed descriptions of trace options

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