Unloading providers (again)

Hi,

I've stumbled upon strange crashes when onloading OpenLMI providers:

1. at startup, cimprovagt:
  1.1 creates a thread pool
  1.2 dlopens our provider
     1.2.1 the dlopen() loads all dependencies, libglib-2.0 among others

2. the provider servers various CIM methods
  2.1 as we use libglib2, it registers some cleanup functions as thread
local storage destructors (see man pthread_key_create).

3. at cimprovagt shutdown:
  3.1 cimprovagt dlcloses our provider
     3.1.1  which unloads libglib-2.0
  3.2 cimprovagt closes all threads in its threadpool
    3.2.1 thread local storage destructor callbacks are called, but
libglib2 is already unloaded from memory -> SIGSEGV

Now, is there a way how to fix it?

It's not possible to un-register the glib2 callbacks - the local storage
destructors must be removed from the thread which registered them and
only cimprovagt has access to the threads.

The only generic soluton I know is to destroy the thread pool first and
dlclose() providers after that. Looking at ProviderAgent.cpp, it looks
like lot of work since one ProviderAgent.cpp may handle multiple
providers and they can be unloaded dynamically, not only at cimprovgt
shutdown, right? (Note that OpenLMI uses only one provider per
cimprovagt process so it might be a bit easier in our case).

Any other idea?

Of course, I can try to prevent libglib from being unloaded on dlclose()
using some dirty hacks in our provider. But that's just a workaround.


Jan