pthread_yield_np(3) Library Functions Manual pthread_yield_np(3)
NAME
pthread_yield_np - Notifies the scheduler that the current thread is willing to release its processor to other threads of the same or
higher priority.
LIBRARY
DECthreads POSIX 1003.1c Library (libpthread.so)
SYNOPSIS
#include <pthread.h>
int pthread_yield_np(
void);
STANDARDS
Interfaces documented on this reference page conform to industry standards as follows:
IEEE Std 1003.1c-1995, POSIX System Application Program Interface
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 call-
ing 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_np(3), other threads may be given the opportunity to run at arbitrary points (possibly even when the interrupted thread holds
a required resource). By making strategic calls to pthread_yield_np(3), other threads may 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
If an error condition occurs, this routine returns an integer value indicating the type of error. Possible return values are as follows:
Successful completion. The routine is not supported by this implementation.
ERRORS
None
RELATED INFORMATION
Functions: pthread_attr_setschedparam(3), pthread_setschedparam(3), pthread_getscheduler(3)
Manuals: Guide to DECthreads and Programmer's Guide
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pthread_yield_np(3)