Where is the .NET JIT-compiled code cached?

Question

A .NET program is first compiled into MSIL code. When it is executed, the JIT compiler will compile it into native machine code.

I am wondering:

Where is th

Answer 1

As others have pointed out, code is JIT'd on a per process basis in your case, and is not cached - the speed-up you are seeing on second load is OS disk caching (i.e. in-memory) of the assemblies.

However, whilst there is no caching (apart from OS disk caching) in the desktop\server version of the framework, there is caching of JIT'd machine code in another version of the framework.

Of interest is what is happening in the .Net Compact Framework (NETCF for Windows Phone 7 relase). Recent advances see sharing of some JIT'd framework code between processes where the JIT'd code is indeed cached. This has been primarily carried out for better performance (load time and memory usage) in constrained devices such as mobile phones.

So in answer to the question there is no direct framework caching of JIT'd code in the desktop\server version of the CLR, but there will be in the latest version of the compact framework i.e. NETCF.

Reference: We Believe in Sharing

http://blogs.msdn.com/b/abhinaba/archive/2010/04/28/we-believe-in-sharing.aspx