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PTHREAD_ATTR_INIT(3)							     PTHREAD_ATTR_INIT(3)

NAME
       pthread_attr_init,  pthread_attr_destroy, pthread_attr_setdetachstate, pthread_attr_getde-
       tachstate, pthread_attr_setschedparam, pthread_attr_getschedparam,  pthread_attr_setsched-
       policy,	pthread_attr_getschedpolicy, pthread_attr_setinheritsched, pthread_attr_getinher-
       itsched, pthread_attr_setscope, pthread_attr_getscope - thread creation attributes

SYNOPSIS
       #include <pthread.h>

       int pthread_attr_init(pthread_attr_t *attr);

       int pthread_attr_destroy(pthread_attr_t *attr);

       int pthread_attr_setdetachstate(pthread_attr_t *attr, int detachstate);

       int pthread_attr_getdetachstate(const pthread_attr_t *attr, int *detachstate);

       int pthread_attr_setschedpolicy(pthread_attr_t *attr, int policy);

       int pthread_attr_getschedpolicy(const pthread_attr_t *attr, int *policy);

       int pthread_attr_setschedparam(pthread_attr_t *attr, const struct sched_param *param);

       int pthread_attr_getschedparam(const pthread_attr_t *attr, struct sched_param *param);

       int pthread_attr_setinheritsched(pthread_attr_t *attr, int inherit);

       int pthread_attr_getinheritsched(const pthread_attr_t *attr, int *inherit);

       int pthread_attr_setscope(pthread_attr_t *attr, int scope);

       int pthread_attr_getscope(const pthread_attr_t *attr, int *scope);

DESCRIPTION
       Setting attributes for threads is achieved by filling a thread attribute  object  attr  of
       type  pthread_attr_t,  then  passing  it as second argument to pthread_create(3).  Passing
       NULL is equivalent to passing a thread attribute object with all attributes set	to  their
       default values.

       pthread_attr_init  initializes  the thread attribute object attr and fills it with default
       values for the attributes. (The default values are listed below for each attribute.)

       Each attribute attrname (see below for a list of all attributes) can be	individually  set
       using   the   function	pthread_attr_setattrname   and	 retrieved   using  the  function
       pthread_attr_getattrname.

       pthread_attr_destroy destroys a thread attribute object, which must not be reused until it
       is reinitialized.  pthread_attr_destroy does nothing in the LinuxThreads implementation.

       Attribute objects are consulted only when creating a new thread. The same attribute object
       can be used for creating several threads. Modifying an attribute object after  a  call  to
       pthread_create does not change the attributes of the thread previously created.

       The following thread attributes are supported:

   detachstate
       Control	whether  the  thread is created in the joinable state (value PTHREAD_CREATE_JOIN-
       ABLE) or in the detached state ( PTHREAD_CREATE_DETACHED).

       Default value: PTHREAD_CREATE_JOINABLE.

       In the joinable state, another thread  can  synchronize	on  the  thread  termination  and
       recover	its  termination code using pthread_join(3), but some of the thread resources are
       kept allocated after the thread terminates, and reclaimed only when  another  thread  per-
       forms pthread_join(3) on that thread.

       In  the detached state, the thread resources are immediately freed when it terminates, but
       pthread_join(3) cannot be used to synchronize on the thread termination.

       A thread created in the joinable state can later be  put  in  the  detached  thread  using
       pthread_detach(3).

   schedpolicy
       Select  the  scheduling	policy	for the thread: one of SCHED_OTHER (regular, non-realtime
       scheduling), SCHED_RR (realtime, round-robin) or  SCHED_FIFO  (realtime,  first-in  first-
       out). See sched_setpolicy(2) for more information on scheduling policies.

       Default value: SCHED_OTHER.

       The  realtime  scheduling policies SCHED_RR and SCHED_FIFO are available only to processes
       with superuser privileges.

       The scheduling policy of a thread can be changed  after	creation  with	pthread_setsched-
       param(3).

   schedparam
       Contain	the  scheduling parameters (essentially, the scheduling priority) for the thread.
       See sched_setparam(2) for more information on scheduling parameters.

       Default value: priority is 0.

       This attribute is not significant if the scheduling policy is SCHED_OTHER; it only matters
       for the realtime policies SCHED_RR and SCHED_FIFO.

       The  scheduling	priority of a thread can be changed after creation with pthread_setsched-
       param(3).

   inheritsched
       Indicate whether the scheduling policy and scheduling parameters  for  the  newly  created
       thread  are  determined	by the values of the schedpolicy and schedparam attributes (value
       PTHREAD_EXPLICIT_SCHED)	 or   are   inherited	from	the    parent	 thread    (value
       PTHREAD_INHERIT_SCHED).

       Default value: PTHREAD_EXPLICIT_SCHED.

   scope
       Define  the  scheduling contention scope for the created thread.  The only value supported
       in the LinuxThreads implementation is PTHREAD_SCOPE_SYSTEM, meaning that the threads  con-
       tend for CPU time with all processes running on the machine. In particular, thread priori-
       ties are interpreted relative to the priorities of all other processes on the machine. The
       other  value  specified by the standard, PTHREAD_SCOPE_PROCESS, means that scheduling con-
       tention occurs only between the threads of the  running	process:  thread  priorities  are
       interpreted  relative to the priorities of the other threads of the process, regardless of
       the priorities of other processes.   PTHREAD_SCOPE_PROCESS  is  not  supported  in  Linux-
       Threads.

       Default value: PTHREAD_SCOPE_SYSTEM.

RETURN VALUE
       All  functions  return  0  on success and a non-zero error code on error.  On success, the
       pthread_attr_getattrname functions also store the current value of the attribute  attrname
       in the location pointed to by their second argument.

ERRORS
       The pthread_attr_setdetachstate function returns the following error codes on error:

	      EINVAL the   specified   detachstate  is	not  one  of  PTHREAD_CREATE_JOINABLE  or
		     PTHREAD_CREATE_DETACHED.

       The pthread_attr_setschedparam function returns the following error codes on error:

	      EINVAL the priority specified in param is outside the range of  allowed  priorities
		     for  the  scheduling  policy  currently  in attr (1 to 99 for SCHED_FIFO and
		     SCHED_RR; 0 for SCHED_OTHER).

       The pthread_attr_setschedpolicy function returns the following error codes on error:

	      EINVAL the specified policy is not one of SCHED_OTHER, SCHED_FIFO, or SCHED_RR.

	      ENOTSUP
		     policy is SCHED_FIFO or SCHED_RR, and the	effective  user  of  the  calling
		     process is not super-user.

       The pthread_attr_setinheritsched function returns the following error codes on error:

	      EINVAL the   specified   inherit	 is   not   one   of   PTHREAD_INHERIT_SCHED   or
		     PTHREAD_EXPLICIT_SCHED.

       The pthread_attr_setscope function returns the following error codes on error:

	      EINVAL the   specified   scope   is   not   one	 of    PTHREAD_SCOPE_SYSTEM    or
		     PTHREAD_SCOPE_PROCESS.

	      ENOTSUP
		     the specified scope is PTHREAD_SCOPE_PROCESS (not supported).

AUTHOR
       Xavier Leroy <Xavier.Leroy@inria.fr>

SEE ALSO
       pthread_create(3), pthread_join(3), pthread_detach(3), pthread_setschedparam(3).

					   LinuxThreads 		     PTHREAD_ATTR_INIT(3)
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