pthread_getconcurrencypthread_setconcurrency
- get or set level of concurrency
LIBRARY
Lb libpthread
SYNOPSIS
#include <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,
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
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:
Bq Er EINVAL
The value specified by
Fa new_level
is negative.
Bq Er EAGAIN
The value specified by
Fa 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
St -susv2 .
