Does COM automatically unload DLLs when there are no more object references?

Question

For example, in language X:

let x = CreateOject( "MyProgID" )
x.LateBoundCall()
x.Release()  // (or setting x to Nothing in VB-like language, etc)

What happens to the DLL MyProgID lives in? Does COM unload DLLs automatically?

EDIT

This is assuming that the code above is in an executable that does not expose any COM.

Answer 1

you have to manually release the resources used by COM objects. they use a ref counter internally to keep the number of references to the component. if the component still has a refcounter > 0, then the dll will not unload and the resources will not be freed.

Answer 2

Yes, but not in a deterministic way. Windows periodically asks every loaded DLL "is it safe to unload you now?" Any DLL that responds "Yes" is unloaded.

Note a remark from MSDN :

If a DLL loaded through a call to CoGetClassObject fails to export DllCanUnloadNow, the DLL will not be unloaded until the application calls the CoUninitialize function to release the OLE libraries.

See this Old New Thing article.