pthread_getconcurrency(3T)												pthread_getconcurrency(3T)

NAME

       pthread_getconcurrency(), pthread_setconcurrency() - get or set the concurrency level of unbound threads

SYNOPSIS

PARAMETERS

	      new_level New concurrency level for the unbound threads in the calling process.

DESCRIPTION

       The  unbound  threads  in  a process may or may not be required to be simultaneously active. By default, the threads implementation ensures
       that a sufficient number of threads are active so that the process can continue to make progress. While this conserves system resources, it
       may  not  produce  the  most effective level of concurrency. The function allows an application to inform the threads implementation of its
       desired concurrency level, new_level.  The actual level of concurrency provided by the system as a result of this function call is unspeci-
       fied.

       If new_level is zero, it will cause the implementation to maintain the concurrency level at its discretion as if were never called.

       The  function returns the value set by a previous call to If the function was not previously called, this function returns zero to indicate
       that the system is maintaining the concurrency level.

       Note: When an application calls it is informing the implementation of its desired concurrency level. The implementation will use this as  a
       hint, not a requirement. A call to immediately after a call to may return a different concurrency level specified in

       If  the	system	does not support the multiplexing of user threads on top of several kernel-scheduled entities, the functions and functions
       will be provided for source code compatibility, but they shall have no effect  when  called.   To  maintain  the  function  semantics,  the
       new_level parameter will be saved when is called so that a subsequent call to will return the same value.

RETURN VALUE

       If successful, returns zero. Otherwise, an error number is returned to indicate the error (the variable is not set).

       The function always returns the concurrency level set by a previous call to If the function has never been called, shall return zero.

ERRORS

       If any of the following occur, the function shall return the corresponding error number.

	      [EINVAL]	     The value specified by new_level is invalid.

	      [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 level upon which the application depends. Library developers are
       advised to not use the and functions as their use may conflict with an applications use of these functions.

AUTHOR

       and were developed by X/Open.

SEE ALSO

       pthread_num_processors_np(3T), pthread_processor_bind_np(3T), pthread_processor_id_np(3T).

STANDARDS CONFORMANCE

								  Pthread Library					pthread_getconcurrency(3T)