what functions are included in a JVM

What are the functions of the JVM? All I know are:

• JIT compiler
• GC
• memory allocator

What are the steps it does when you load a Java application?

I am wonder开发者_C百科ing because if I compare the loading time of a Java application with these steps:

• InitializeNativeTarget on LLVM
• some GC initialization
• some Qt/GTK/whatever init
• some JIT/ahead compilation of parts of the app
• the app init itself

It seems to me that the JVM takes much longer to load than it would take to do the steps I listed above. So what does it do in addition to that?

That's actually a very interesting question - to see for yourself, run a Hello World program giving the option -XX:-TraceClassLoading to the java executable.

It bootstraps the whole JVM from scratch. That takes a while.