Abhishek Mahanty's Weblog

HotSpot JVM Options

There are a number of parameters/options you can provide while creating a Java HotSpot VM. The options fall under the following 3 categories:

• Standard - To list out the standard options do: java -help
  

      abhi@abhiltlnx(~)# java -help
      Usage: java [-options] class [args...]
                 (to execute a class)
         or  java [-options] -jar jarfile [args...]
                 (to execute a jar file)
  
      where options include:
          -d32          use a 32-bit data model if available
  
          -d64          use a 64-bit data model if available
          -client       to select the "client" VM
          -server       to select the "server" VM
          -hotspot      is a synonym for the "client" VM  [deprecated]
                        The default VM is client.
  
          -cp 
          -classpath 
                        A : separated list of directories, JAR archives,
                        and ZIP archives to search for class files.
          -D=
                        set a system property
          -verbose[:class|gc|jni]
                        enable verbose output
          -version      print product version and exit
          -version:
                        require the specified version to run
          -showversion  print product version and continue
          -jre-restrict-search | -jre-no-restrict-search
                        include/exclude user private JREs in the version search
          -? -help      print this help message
          -X            print help on non-standard options
          -ea[:...|:]
          -enableassertions[:...|:]
                        enable assertions
          -da[:...|:]
          -disableassertions[:...|:]
                        disable assertions
          -esa | -enablesystemassertions
                        enable system assertions
          -dsa | -disablesystemassertions
                        disable system assertions
          -agentlib:[=]
                        load native agent library , e.g. -agentlib:hprof
                          see also, -agentlib:jdwp=help and -agentlib:hprof=help
          -agentpath:[=]
                        load native agent library by full pathname
          -javaagent:[=]
                        load Java programming language agent, see java.lang.instrument
          -splash:
                        show splash screen with specified image
  
            

• Non-Standard - To list them out do: java -X
  

      abhi@abhiltlnx(~)# java -X
          -Xmixed           mixed mode execution (default)
          -Xint             interpreted mode execution only
          -Xbootclasspath:
                            set search path for bootstrap classes and resources
          -Xbootclasspath/a:
                            append to end of bootstrap class path
          -Xbootclasspath/p:
                            prepend in front of bootstrap class path
          -Xnoclassgc       disable class garbage collection
          -Xincgc           enable incremental garbage collection
          -Xloggc:    log GC status to a file with time stamps
          -Xbatch           disable background compilation
          -Xms        set initial Java heap size
          -Xmx        set maximum Java heap size
          -Xss        set java thread stack size
          -Xprof            output cpu profiling data
          -Xfuture          enable strictest checks, anticipating future default
          -Xrs              reduce use of OS signals by Java/VM (see documentation)
          -Xcheck:jni       perform additional checks for JNI functions
          -Xshare:off       do not attempt to use shared class data
          -Xshare:auto      use shared class data if possible (default)
          -Xshare:on        require using shared class data, otherwise fail.
  
      The -X options are non-standard and subject to change without notice.
  
            

• Hidden - Well as the name suggests, they are hidden. These options typically have a -XX prefix
  

To learn more about the HotSpot JVM options - http://java.sun.com/javase/technologies/hotspot/vmoptions.jsp

I found a great resource that lists various JVM versions and the corresponding options. http://blogs.sun.com/watt/resource/jvm-options-list.html

Posted at 12:00AM Feb 16, 2008 by Abhishek Mahanty in Technical  |  Comments[0]