Is there a way to delete module when needed? My problem is that when I discard a module it isn't deleted since it has non zero context reference count. In my app, I have a pool of contexts from which I take unused one and execute function with it, at the moment I load 2 scripts, the second one is loaded during execution of the first one, so they have different contexts assigned to them. When I try to delete modules (engine->Discard), they're not deleted at all, even though none of them is executing.

They are not deleted since the contexts still hold references to them (as you accurately noted). The contexts free their references to the module when they themselves are released, or if they are prepared with another function.

The call to engine->Discard() only sets a flag for the module that says that it is not to be used anymore for new calls. You will not be able to prepare a context with a function from a discarded module. The module name is also freed so that you can compile another module reusing the name.

Regards,
Andreas