On Wed, Mar 13, 2013 at 9:40 AM, ishare <june.tune....@gmail.com> wrote:
> On Tue, Mar 12, 2013 at 06:18:02PM +0530, Prabhu nath wrote: > > I guess we should not mix mutex and condition variable. Both have their > own > > respective semantics. > > *mutex* is used to serialize access to a shared resource among competing > > threads. > > *condition variable* is used to notify a* state change* of a resource to > > the interested thread. > > > > In case of condition variable there is provision to explicitly notify a > > single thread(pthread_cond_signal) or all the threads waiting on a > > condition (or a state change) (pthread_cond_broadcast) > > > > Question was on pthread_mutex_unlock() that whether this function > > invocation will trigger the movement of all the threads in the wait queue > > to the ready queue. > > After pthread_mutex_unlock() is called , the mutex is release , then > ,which stuff > will reshcedule the threads in the waitqueue ? > > If do pthread_cond_signal() after each pthread_mutex_unlock() ,does it > raise up the performence ? > > thanks! > I think you are missing something in your understanding. Please refer "Programming with POSIX threads" - David R. Butenhof > > > > > > > If all the threads are of equal priority, then the first thread waiting > for > > the lock will be put to READY queue. > > If there are variable priority threads waiting for the lock, then the > > thread with highest priority would be woken up > > > > -- Regards, Prabhunath G Linux Trainer Bangalore
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