Question

I am sorry I am repeating a question https://stackoverflow.com/questions/5687837/monitor-implementation-in-c but not getting a solution as yet. I have probably asked the question incorrectly.

Say I have a code portion B. A parent process spawns a number of child processes to execute code B but I would like only one process to be inside code portion B at a time. How can I do it in C on Linux platform?

Thanks for your help

An edit. Not threads but process.

Answer 1

You want a mutex.

pthread_mutex_t mutexsum;
pthread_mutex_init(&mutexsum, NULL);
pthread_mutex_lock (&mutexsum);
// Critical code
pthread_mutex_unlock (&mutexsum);

If you are serious about it being multiple processes instead of multiple threads, the mutex needs to be stored in a shared memory segment.