Roland wrote: [...]
http://google.com/groups?selm=406ECF36.226C8B99%40web.de (Subject: Re: TSD key reuse)
This post mentions the necessity that ~thread_specific_ptr needs to deallocate the slot. Is this really necessary?
Windows zaps the slots asynchronously if you do TlsFree. http://groups.google.com/groups?selm=3f5d1aee%241%40news.microsoft.com <quote author=Neill Clift [MSFT]> we do cross thread clearing of tls slots when its deleted by one thread. </quote> This is needed for thread_specific_ptr< T, no_cleanup > objects.
I see two different areas of concern: 1) Process termination: Not really a need to free the native slot, since the process is going away anyways.
Right.
Also I think no current memory debugging utility will bother with native slots. 2) DLL detachment: It is essential to free the native slot, since not doing so prevents reuse.
Right.
However this will be bad for connected threads. There seems to exist some principal coupling between the lifetime of a thread and lifetime of a DLL, which is not enforced by the operating system.
The entire application shall stop using the DLL by the time it unloads it. "dll_fini" will deallocate the slots. Now see above. Having "thread insensible TSD dtros" wouldn't hurt either...
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How is the situation for other libraries, say e.g. pthreads? Are they allowed to run after main ended?
Main (initial) *thread* is just a thread, nothing special. Main *function* is special. Return from main is just like calling exit() -- it evaporates all threads without any thread cleanup. OTOH, mere termination of main/initial thread (by means of pthread_exit() or thread cancellation), has no effect with respect to other threads.
This sounds interesting to me. It is really possible to use pthread_exit() to exit the main thread?
Yes. You can also cancel it. pthread_exit(PTHREAD_CANCELED); is a shortcut for pthread_cancel(pthread_self()); pthread_testcancel(); See also http://www.codesourcery.com/archives/c++-pthreads/msg00005.html
And what happens then?
Main/initial thread terminates.
Are the global destuctors called?
Only if main/initial is the last thread.
Or are they held off until the last thread exited?
Yes. regards, alexander.