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what is the output of "java -version"?

You can post the output of uname -a too, if you like. And confirm for us that this is a physical machine and not a virtual one.

and the output of "java -version"? Are you sure you're stopping the previous one before running the next one? You should have nearly 2G free before starting java

If your system can't allocate memory, it doesn't have it to spare. What command line are you using? For example this doesn't work on my PC:

java -Xms22G -version
Error occurred during...

Always copy-paste error messages. Perhaps you don't have as much memory spare as you're trying to give to Java? Are you running more than one instance of your program?