What are the default -Xmx and -Xms values?

Happened to read Inspecting HotSpot JVM Options and found a solution to one of the questions that I have every now and then. What are the default -Xmx and -Xms values for this JVM on this machine? The solution? Invoking java with some flags, check out the terminal session.

toomasr@cigarillo-2:~$ java -server -XX:+UnlockDiagnosticVMOptions -XX:+PrintFlagsFinal -version | grep -i heapsize
uintx ErgoHeapSizeLimit                    = 0                {product}
uintx InitialHeapSize                     := 65011712         {product}
uintx LargePageHeapSizeThreshold           = 134217728        {product}
uintx MaxHeapSize                         := 1040187392       {product}
java version "1.6.0_22"
Java(TM) SE Runtime Environment (build 1.6.0_22-b04-307-10M3261)
Java HotSpot(TM) 64-Bit Server VM (build 17.1-b03-307, mixed mode)
toomasr@cigarillo-2:~$ java -client -XX:+UnlockDiagnosticVMOptions -XX:+PrintFlagsFinal -version | grep -i heapsize
uintx ErgoHeapSizeLimit                    = 0                {product}
uintx InitialHeapSize                      = 0                {product}
uintx LargePageHeapSizeThreshold           = 134217728        {product}
uintx MaxHeapSize                          = 130862280        {product}
java version "1.6.0_22"
Java(TM) SE Runtime Environment (build 1.6.0_22-b04-307-10M3261)
Java HotSpot(TM) 64-Bit Server VM (build 17.1-b03-307, mixed mode)

If there is an easier way, let me know. Will put this one on my tool belt at the moment.

This entry was posted on Wednesday, January 12th, 2011 at 10:57 am by Toomas Römer and is filed under cool. You can follow any comments to this entry through the RSS 2.0 feed. You can leave a comment, or trackback from your own site.

  • Mart

    Thanks often wanted to find this out. It works well for Java version “1.6.0_22″ and “1.6.0_23″ but unfortunately fails with “1.6.0_07″ we have the following error :-

    java -server -XX:+UnlockDiagnosticVMOptions -XX:+PrintFlagsFinal -version | grep -i heapsize
    Unrecognized VM option ‘+PrintFlagsFinal’
    Could not create the Java virtual machine.

  • http://twitter.com/toomasr Toomas Römer

    Wow, this sucks. Went over the Java 5 options and could not find an equivalent. I guess this only works for latest Java 6 builds.

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  • Zahid1705

    this only works for Java 6u20 and later