pthread_yield(3) — Subroutines
NAME
pthread_yield − Notifies the scheduler that the current thread is willing to release its processor to other threads of the same or higher priority.
SYNOPSIS
#include <pthread.h>
void pthread_yield( );
PARAMETERS
None.
DESCRIPTION
This routine notifies the thread scheduler that the current thread is willing to release its processor to other threads of equivalent or greater scheduling precedence. (A thread generally will release its processor to a thread of a greater scheduling precedence without calling this routine.) If no other threads of equivalent or greater scheduling precedence are ready to execute, the thread continues.
This routine can allow knowledge of the details of an application to be used to improve its performance. If a thread does not call pthread_yield, other threads may be given the opportunity to run at arbitrary points (possibly even when the interupted thread holds a required resource). By making strategic calls to pthread_yield, other threads can be given the opportunity to run when the resources are free. This improves performance by reducing contention for the resource.
As a general guideline, consider calling this routine after a thread has released a resource (such as a mutex) which is heavily contended for by other threads. This can be especially important if the program is running on a uniprocessor machine, or if the thread acquires and releases the resource inside a tight loop.
Use this routine carefully and sparingly, because misuse can cause unnecessary context switching which will increase overhead and actually degrade performance. For example, it is counter-productive for a thread to yield while it holds a resource which the threads to which it is yielding will need. Likewise, it is pointless to yield unless there is likely to be another thread which is ready to run.
RETURN VALUES
None.