[SOLVED] pthread : pthread_cond_wait

[kingsmasher1]

Hello All,
I was studying pthreads today.
If multiple threads operate on a single shared resource, we can lock it using pthread_mutex_lock. Uptill that it is fine, but why again pthread_cond_wait?

int shared=0; // global
.
.
// Thread 1
pthread_mutex_lock(&mutex);
shared=1;
pthread_mutex_unlock(&mutex);

When thread1 invokes the mutex lock, no other threads can access it in parallel. So why again and what for we use, pthread_cond_wait( ). Someone kindly help me with a good code example.

[abienkowski]

pthread_cond_wait is used in cases where one thread needs to wait for another thread to complete a job in order to proceed. In such cases you don't want to be sleeping and polling a state, you simply want to be notified when things are done and you can proceed.

This function also with pthread_cond_timedwait and be used to implement a message queue for message passing between threads. In an event driven software design architecture.

[kingsmasher1]

pthread_cond_wait is used in cases where one thread needs to wait for another thread to complete a job in order to proceed. In such cases you don't want to be sleeping and polling a state, you simply want to be notified when things are done and you can proceed.

This function also with pthread_cond_timedwait and be used to implement a message queue for message passing between threads. In an event driven software design architecture.

Thanks, this solves.