Top Most What is maximum Java Heap Size for 32 bit and 64-bit JVM - Frequently asked Questions

Maximum heap size  for 32 bit or 64 bit JVM looks easy to determine by looking at addressable memory space like 2^32 (4GB) for 32 bit JVM and 2^64 for 64 bit JVM. Confusion starts here because you can not really set 4GB as maximum heap size for 32 bit JVM using -Xmx JVM heap options. You will get could not create the Java virtual machine Invalid maximum heap size: -Xmx  error. There could be many different reason why maximum heap space for JVM is less than there theoretical limit and vary from one operating system to other e.g. different in Windows, Linux and Solaris. I have seen couple of comments on my post 10 points on Java Heap Spaceregarding what is maximum heap space for Java or 32 bit JVM or 64 bit JVM and why Windows allows only upto 1.6G memory as maximum heap space etc. In this Java article, I have collected some of the frequently asked questions around maximum heap space on both 32 and 64 bit JVM and tried to explain them.

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