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PTHREAD_GETCONCURRENCY (3) | C library functions | Unix Manual Pages | :man▋
NAME
pthread_getconcurrency, pthread_setconcurrency - get or set level of concurrency
CONTENTS
Library
Synopsis
Description
Return Values
Errors
Application Usage
Standards
LIBRARY
.Lb libc_r
.Lb libpthread
.Lb libthr
SYNOPSIS
.In pthread.h int pthread_getconcurrency void int pthread_setconcurrency "int new_level"
DESCRIPTION
The pthread_getconcurrency function allows an application to inform the threads implementation of its desired concurrency level, new_level. The actual level of concurrency provided by the implementation as a result of this function call is unspecified. If new_level is zero, it causes the implementation to maintain the concurrency level at its discretion as if pthread_setconcurrency was never called. The pthread_getconcurrency function returns the value set by a previous call to the pthread_setconcurrency function. If the pthread_setconcurrency function was not previously called, this function returns zero to indicate that the implementation is maintaining the concurrency level. When an application calls pthread_setconcurrency, it is informing the implementation of its desired concurrency level. The implementation uses this as a hint, not a requirement.
RETURN VALUES
If successful, the pthread_setconcurrency function returns zero. Otherwise, an error number is returned to indicate the error. The pthread_getconcurrency function always returns the concurrency level set by a previous call to pthread_setconcurrency. If the pthread_setconcurrency function has never been called, pthread_getconcurrency returns zero.
ERRORS
The pthread_setconcurrency function will fail if: | [EINVAL] | | | The value specified by new_level is negative. | | [EAGAIN] | | | The value specified by new_level would cause a system resource to be exceeded. | |
APPLICATION USAGE
Use of these functions changes the state of the underlying concurrency upon which the application depends. Library developers are advised to not use the pthread_getconcurrency and pthread_setconcurrency functions since their use may conflict with an application’s use of these functions.
STANDARDS
The pthread_getconcurrency and pthread_setconcurrency functions conform to -susv2. | April 11, 2003 | PTHREAD_GETCONCURRENCY (3) | |
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