Multithreaded Programming Guide

Return Values

Returns a zero when it completes successfully. Any other returned value indicates that an error occurred. When any of the following conditions are detected, pthread_join() fails and returns the corresponding value.


tid is not a valid, undetached thread in the current process.


tid specifies the calling thread.


The value of tid is invalid.

The pthread_join() routine takes two arguments, giving you some flexibility in its use. When you want the caller to wait until a specific thread terminates, supply that thread's ID as the first argument.

If you are interested in the exit code of the defunct thread, supply the address of an area to receive it.

Remember that pthread_join() works only for target threads that are nondetached. When there is no reason to synchronize with the termination of a particular thread, then that thread should be detached.

Think of a detached thread as being the thread you use in most instances and reserve nondetached threads for only those situations that require them.