PTHREAD_GETCONCURRENCY(3) BSD Programmer's Manual PTHREAD_GETCONCURRENCY(3)
pthread_getconcurrency, pthread_setconcurrency - get or set level of con-
currency
#include <pthread.h>
int
pthread_getconcurrency(void);
int
pthread_setconcurrency(int new_level);
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() func-
tion was not previously called, this function returns zero to indicate
that the implementation is maintaining the concurrency level. When an ap-
plication calls pthread_setconcurrency(), it is informing the implementa-
tion of its desired concurrency level. The implementation uses this as a
hint, not a requirement.
If successful, the pthread_setconcurrency() function returns zero. Other-
wise, 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.
pthread_setconcurrency() 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.
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 func-
tions.
The pthread_getconcurrency() and pthread_setconcurrency() functions con-
form to Version 2 of the Single UNIX Specification.
MirOS BSD #10-current April 11, 2003 1
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