Comment by epmos

This is moderately common for environments where you are pushing a lot of startup work into the dynamic linker and will be launching processes frequently. Loading shared libraries for example.

You have a parent process which uses dlopen() to load all the libraries you want to avoid re-linking. When you want to spawn a child, rather than exec() you dlopen() an object with your child's main() and call it. For the case where you have enough libraries this is much faster than an exec(), saving tens of seconds on every application launch if you have a really bad case of C++.

There some small surprises which become obvious with a little thought. You are responsible for everything that normally happens in your process before main() is called. ASLR is only done once per session. People rarely think to fix-up argv[] for ps and friends in the first version.