cowwoc
Peter Dimov-5 wrote:
exit() will not hang, it will just terminate the thread (and all other threads) as its very last step (after invoking the atexit handlers and global/static destructors).
But what happens if one of the handlers is itself waiting for the thread to shut down?
If an atexit handler waits for a thread to shut down then it will block. If it is waiting for its own thread to shutdown then you have deadlock. That's easy to fix --- just set a flag to indicate to the atexit handler not to wait for this thread before you call exit.
Also, is at_thread_exit() implemented as an atexit() handler under the hood?
at_thread_exit is completely unrelated to atexit. It runs a function when the thread that called at_thread_exit returns from its thread function. For threads started with boost::thread this is done as part of the boost::thread internal thread management code. For threads started with platform-specific facilities such as CreateThread or pthread_create it is done using platform-specific hooks. Again, these do not interact with atexit handlers.
If not, how do you prevent it from killing the hook functions prematurely?
Calling exit() terminates all threads abruptly once the atexit handlers have run. Thread exit functions are not run for any threads. If threads are running at_thread_exit hooks they are terminated just as abruptly. Anthony -- Author of C++ Concurrency in Action | http://www.manning.com/williams just::thread C++0x thread library | http://www.stdthread.co.uk Just Software Solutions Ltd | http://www.justsoftwaresolutions.co.uk 15 Carrallack Mews, St Just, Cornwall, TR19 7UL, UK. Company No. 5478976