PTHREAD_GET pthread_getconcurrency, pthread_setconcurrency - get or set
level of concurrency
#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() 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.
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.
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
functions.
The pthread_getconcurrency() and pthread_setconcurrency()
functions conform
to Version 2 of the Single UNIX Specification.
OpenBSD 3.6 April 11, 2003
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