On 07/26/2010 11:25 AM, Anthony Williams wrote:
I have thought about this problem lots, and decided that you cannot safely interrupt a condition variable wait on POSIX unless you have a mutex tied directly to each condition variable (as with condition_variable_any). I'm therefore not sure how to approach this --- either every boost::condition_variable has an extra pthread_mutex_t inside it, or interruption is limited to waits on boost::condition_variable_any.
I have to look in detail the boost::thread implementation to help you here. Is pthread_cancel() still a no go to be used in threads::interrupt implementation? Another source of hang with notify_all (and then with interrupt), is the following usage pattern: 1. Thread A: acquires a lock on mutex Ma 2. Thread A: does a wait on the condition C: C.wait(Ma) 3. Thread B: acquires a lock on mutex Mb 4. Thread B: does a wait on the condition C: C.wait(Mb) at this point a C.notify_all() doesn't awakes both threads, in order to awake both threads two C.notify_one() calls are needed. Regards Gaetano Mendola