Using JVM options

When using the Java interface, you can instruct fglrun or fglcomp to pass Java VM specific options during JNI initialization, by using the --java-option command line argument.

In the example, fglrun passes -verbose:gc to the Java Virtual Machine:

$ fglrun --java-option=-verbose:gc myprog.42m

If you want to pass several options to the JVM, repeat the --java-option argument as in this example:

$ fglrun --java-option=-verbose:gc --java-option=-esa myprog.42m

You may want to pass the Java class path as a command line option to fglrun with -Djava.class.path option as in this example:

$ fglrun --java-option=-Djava.class.path=$FGLDIR/lib/fgl.jar:$MYCLASSPATH
 myprog.42m

Regarding class path specification, the java runtime or javac compiler provides the -cp or -classpath options but when loading the JVM library from fglrun or fglcomp, only -Djava.class.path option is supported by the JNI interface.

Alternatively, you can define JVM options with the JAVA_TOOL_OPTIONS environment variable:

$ export JAVA_TOOL_OPTIONS="-Xmx5G"
$ fglrun myprog.42m

However, this solution can have some limitations. For more details, see the Java documentation.