PTHREAD_ATTR_INIT(3)                         PTHREAD_ATTR_INIT(3)

NAME
       pthread_attr_init, pthread_attr_destroy, pthread_attr_set-
       detachstate,                  pthread_attr_getdetachstate,
       pthread_attr_setschedparam,    pthread_attr_getschedparam,
       pthread_attr_setschedpolicy,  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).  Pass-
       ing 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_JOINABLE) 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    performs
       pthread_join(3) on that thread.

       In  the  detached  state, the thread resources are immedi-
       ately 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_setschedparam(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_setschedparam(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 contend for CPU time with all processes running on
       the machine. In particular, thread priorities  are  inter-
       preted  relative  to the priorities of all other processes
       on the machine. The other value specified by the standard,
       PTHREAD_SCOPE_PROCESS,  means  that  scheduling contention
       occurs only between the threads of  the  running  process:
       thread  priorities are interpreted relative to the priori-
       ties of the other threads of the  process,  regardless  of
       the  priorities of other processes.  PTHREAD_SCOPE_PROCESS
       is not supported in LinuxThreads.

       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 argu-
       ment.

ERRORS
       The pthread_attr_setdetachstate function returns the  fol-
       lowing error codes on error:

              EINVAL the  specified  detachstate  is  not  one of
                     PTHREAD_CREATE_JOINABLE   or    PTHREAD_CRE-
                     ATE_DETACHED.

       The  pthread_attr_setschedparam  function returns the fol-
       lowing 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  fol-
       lowing 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 fol-
       lowing 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_PRO-
                     CESS.

              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                         1