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Java 2 SDK for Solaris Developer's Guide

Command-Line Differences Between the Java 2 SDK and JDK 1.1

VM-Specific (Non-Standard) Options

The reference implementation of Java 2 SDK for Solaris divides options into two groups. One group includes options specific to a particular VM; the other group applies to all VMs. Each group has its own option syntax. VM-specific options all start with -X; for example, -Xdebug to enable debugging. Using the -X by itself produces a help message listing all the VM-specific options that this implementation accepts.

Java 2 SDK for Solaris supports these -X options shown in the table below:

Table 4-1 Currently Accepted -X Options

-X

Lists available options 

-Xbootclasspath[/a|/p]:<path>

Sets, appends to, or prepends to boot class path 

-Xdebug

Enables remote debugging 

-Xmaxjitcodesize

Sets the maximum size in bytes for the JIT compiler code area 

-Xms

Sets initial Java heap size 

-Xmx <size>

Sets maximum Java heap size 

-Xnoclassgc

Disables class garbage collection 

-Xoptimize

(SPARC only) Experimental only. Spend more time optimizing methods in the JIT. This option will most likely benefit long-running CPU-bound applications and might result in increased performance of your application. 

-Xoss<size>

Sets maximum Java stack size for any thread 

-Xrs

Reduces the use of OS signals 

-Xrunhprof [:file=<file>,depth=<n>]

Outputs heap profile to java.hprof.txt or <file>

-Xsqnopause

Does not pause for user interaction on SIGQUIT.

-Xss <size>

Sets the maximum native stack size for any thread 

-Xt

Turns on instruction tracing 

-Xtm 

Turns on method tracing 

Note -

The -X options are subject to change without notice.

Many of these options correspond to JDK 1.1.1-1.1.6 options. Refer to the next section for more information.

Also, although these -X options are VM specific, many of them are sufficiently generic that any reasonably useful VM would provide them. Also, Java 2 SDK for Solaris does not support the following reference platform -X option whereas it is supported in the reference release:

-Xnoasyncgc

Disables asynchronous garbage collection 

Option Compatibility

The following JDK 1.1 compatibility options are currently allowed:

oldjava Utility

The oldjava utility provides greater compatibility with the JDK 1.1-based java utility. When you invoke oldjava, the -classpath command-line option and CLASSPATH environmental variable are treated as in JDK 1.1 release. Certain new Java 2 SDK for Solaris options are disabled (in particular the -jar option).