Why isn't more Java software compiled natively?

Question

I realize the benefits of bytecode vs. native code (portability).

But say you always know that your code will run on a x86 architecture, why not then compile for x86 and get the performance benefit?

Note that I am assuming there is a performance gain to native code compilation. Some folks have answered that there could in fact be no gain which is news to me..

Answer 1

Because the performance gain (if any) is not worth the trouble.

Also, garbage collection is very important for performance. Chances are that the GC of the JVM is better than the one embedded in the compiled executable, say with GCJ.

And just in time compilation can even result in better performance because the JIT has more information are run-time available to optimize the compilation than the compiler at compile-time. See the wikipedia page on JIT.

Answer 2

"Solaris" is an operating system, not a CPU architecture. The JVM installed on the actual machine will compile to the native CPU instructions. Solaris could be SPARC, x86, or x86-64 architecture.

Also, the JIT compiler can make processor-specific optimisations depending on which actual CPU family you have. For example, different instruction sequences are faster on Intel CPUs than on AMD CPUs, and a JIT compiler for your exact platform can take advantage of this information to produce highly optimised code.