UNIX for Dummies Questions & Answers

I am trying to understand the exact difference between condition variables and mutexes in thread synchronization ?. I know mutex will control the thread access to shared data and condition variables will be useful for waiting for certain event or condition to occur . But I couldn't understand
why do we need mutex if we want to wait on a condition variable .
My question is on pthread_cond_wait ( ..) <-- which needs a mutex and a condition variable, I have seen one example on using this sub routine .
there he took lock on the mutex first with pthread_mutex_lock and then
he is waiting on pthread_cond_wait ..can somebody explain the logic behind it ? .

Well, it acquires the lock to avoid other threads to use the condition variable which is not yet correctly initialized and thats why you need to hold (amongst other things ?) the lock before any signaling is done ... but i might totally be wrong
Look and read carefully the man pages, you might find something interesting there!

The wait requites a mutex parameter and it does the following:
unlock mutex
wait for signal on condition
lock mutex

If you don't lock the mutex before calling wait, the wait will try to unlock a mutex that doesn't have a lock - if it gets past that, you'll end up with a dangling lock after the wait

I recommend the following: https://computing.llnl.gov/tutorials...itionVariables