pthread_yield_np(3)pthread_yield_np(3)NAMEpthread_yield_np - 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>
int pthread_yield_np(
void );
LIBRARY
DECthreads POSIX 1003.1c Library (libpthread.so)
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards 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 sched‐
uling 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 implemen‐
tation.
ERRORS
None
SEE ALSO
Functions: pthread_attr_setschedparam(3), pthread_setschedparam(3),
pthread_getscheduler(3)
Manuals: Guide to DECthreads and Programmer's Guide
pthread_yield_np(3)