Question

My question is similar to How do I check if a thread is terminated when using pthread?. but i did not quite get an answer.

My problem is…I create a certain number of threads say n. As soon as main detects the exit of any one thread it creates another thread thus keeping the degree of concurrency as n and so on.

How does the main thread detect the exit of a thread. pthread_join waits for a particular thread to exit but in my case it can be any one of the n threads.

Thanks

Answer 1

Most obvious, without restructuring your code as aix suggests, is to have each thread set something to indicate that it has finished (probably a value in an array shared between all threads, one slot per worker thread), and then signal a condition variable. Main thread waits on the condition variable and each time it wakes up, handle all threads that have indicated themselves finished: there may be more than one.

Of course that means that if the thread is cancelled you never get signalled, so use a cancellation handler or don’t cancel the thread.