在具有8GB RAM的系统上无法设置超过4GB的XMX

Question

I need to set

ANT_OPTS=-Xms1024m -Xmx6144m -XX:PermSize=1024m -XX:MaxPermSize=1024m

JAVA_OPTS=-Xms1024m -Xmx6144m -XX:PermSize=1024m -XX:MaxPermSize=1024m

I have a system with 8gb(recently upgraded from 4 gb)

But once i set the ant opts to above said value I am not able to run any of my ant targets and I get the following error

[ERROR] Argument error: -Xmx6144m
[ERROR] Specified maximum heap size (6144 MB) is larger than the address space on this platform (4 GB).
[WARN ] -XX:PermSize=1024m is not a valid VM option. Ignoring
[WARN ] -XX:MaxPermSize=1024m is not a valid VM option. Ignoring
Could not create the Java virtual machine.

This indicates the Java that I have on my system

java version "1.6.0_20"
Java(TM) SE Runtime Environment (build 1.6.0_20-b02)
Oracle JRockit(R) (build R28.1.0-123-138454-1.6.0_20-20101014-1351-windows-x86_64, compiled mode)

and I am running a Windows 7 on Intel Core 2 Duo 3Ghz processor and 8GB RAM.

PS: I did Google for the error and it was one of my first such occurrences where I did not get any links pointing to the specific solution.

Answer 1

As discussed in the comments:

It would seem that your ANT installation is using a 32-bit JVM. While a 64-bi JVM is in your PATH ANT doesn't obey the JVM in your PATH, it first looks at JAVA_HOME. You can verify this by running $JAVA_HOME/bin/java -version.

You can update your environment to set JAVA_HOME to the 64-bit version or change the ANT script to always use a specific version of Java.

Answer 2

The error message appears to be suggesting the platform is 32-bit. I imagine you can't actually use 4 GB.

I would try installing the 64-bit version of Java and using that.

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For the HotSpot JVM I would expect to see

$ java -mx30g -version
java version "1.6.0_31"
Java(TM) SE Runtime Environment (build 1.6.0_31-b05)
Java HotSpot(TM) 64-Bit Server VM (build 20.6-b01, mixed mode)