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Asked in an interview. What happens if you specify max heap size (Xmx) greater than available RAM?
I also wonder what happens if you specify min heap size (Xms) greater than available RAM?
The easiest way to find out is try it and see.
Edit:
There are actually at least two answers to the question. Probably on a 64 bit system, as was mentioned, your app could grow and grow in memory usage and start thrashing. On a 32 bit system the story is a little different because the os is not able to give you that much heap space. For instance, if I run an app on Windows XP with 32 bit java with the command line option -Xmx2000m it will die with a message similar to the following:
In Linux with 32 bit java, I get the following with -Xmx3000m:
In Linux with 32 bit java, I get the following with -Xmx6000m
Trying this with 64 bit Java, the JVM does allow you to allocate more memory than there is physical RAM, though if you ask for an extremely large amount of memory, the jvm will again fail with an error.