.\" $OpenBSD: pthread_getconcurrency.3,v 1.4 2013/06/05 03:44:50 tedu Exp $ .\" .\" Copyright (c) 2003 Sergey Osokin <osa@FreeBSD.org.ru> .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" $FreeBSD: src/lib/libc_r/man/pthread_getconcurrency.3,v 1.2 2003/05/24 19:50:43 ru Exp $ .Dd $Mdocdate: June 5 2013 $ .Dt PTHREAD_GETCONCURRENCY 3 .Os .Sh NAME .Nm pthread_getconcurrency , .Nm pthread_setconcurrency .Nd get or set level of concurrency .Sh SYNOPSIS .In pthread.h .Ft int .Fn pthread_getconcurrency void .Ft int .Fn pthread_setconcurrency "int new_level" .Sh DESCRIPTION The .Fn pthread_setconcurrency function allows an application to inform the threads implementation of its desired concurrency level, .Fa new_level . The actual level of concurrency provided by the implementation as a result of this function call is unspecified. If .Fa new_level is zero, it causes the implementation to maintain the concurrency level at its discretion as if .Fn pthread_setconcurrency was never called. The .Fn pthread_getconcurrency function returns the value set by a previous call to the .Fn pthread_setconcurrency function. If the .Fn 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 .Fn pthread_setconcurrency , it is informing the implementation of its desired concurrency level. The implementation uses this as a hint, not a requirement. .Sh RETURN VALUES If successful, the .Fn pthread_setconcurrency function returns zero. Otherwise, an error number is returned to indicate the error. The .Fn pthread_getconcurrency function always returns the concurrency level set by a previous call to .Fn pthread_setconcurrency . If the .Fn pthread_setconcurrency function has never been called, .Fn pthread_getconcurrency returns zero. .Sh ERRORS .Fn pthread_setconcurrency will fail if: .Bl -tag -width Er .It Bq Er EINVAL The value specified by .Fa new_level is negative. .It Bq Er EAGAIN The value specified by .Fa new_level would cause a system resource to be exceeded. .El .Sh 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 .Fn pthread_getconcurrency and .Fn pthread_setconcurrency functions since their use may conflict with an application's use of these functions. .Sh STANDARDS The .Fn pthread_getconcurrency and .Fn pthread_setconcurrency functions conform to .St -susv2 .