Is usleep() in C implemented as busy wait?

Question

I'm building a multithreaded application with pthreads and need a thread to periodically check some stuff. During the time in between this thread shouldn't use any CPU. Is this possible with usleep()? Is usleep() not busy waiting? Or is there a better solution?

Answer 1

The function usleep has been removed from SUSv4. You should probably use nanosleep instead or timers (setitimer, etc).

As R.. notes in the comments, should the sleep be implemented as a busy wait:

• The thread would continue to use the CPU
• Other (lower-priority) threads wouldn't get a chance to run

Thus:

• Some might use signals (I think SUSv3 mentioned SIGALARM?)
• Some might use fancy timers