WIN32OLE & Threads incompatible
The WIN32OLE library does not work when using Ruby threads. It may raise exceptions such as this:
connect': failed to parse display name of monikerwinmgmts://localhost/root/cimv2' (WIN32OLERuntimeError)
WIN32 OLE api's are not generally Thread safe, and it can be argued that it is the user's task to ensure that it is accessed only from one thread, or the main thread. However, there are some complications;
- Using WIN32OLE from DRb (DRb can not be used without Threads).
- Using WIN32OLE indirectly (e.g. through Sys::ProcTable).
My specific case was a DRb server that examined processes using Sys::ProcTable, which happen to use WIN32OLE. This causes an exception. Attached is a simple script that recreates the problem. Note that in this simple case, WIN32OLE is only invokes once, and only from one single thread (and it still throws the exception).