NAME

       pthread_exit - thread termination

SYNOPSIS

       #include <pthread.h>

       void pthread_exit(void *value_ptr);

DESCRIPTION

       The  pthread_exit()  function  shall  terminate  the  calling  thread  and  make the value
       value_ptr available to any successful join with the terminating thread.  Any  cancellation
       cleanup  handlers  that have been pushed and not yet popped shall be popped in the reverse
       order that they were pushed and then executed.  After all  cancellation  cleanup  handlers
       have  been  executed,  if  the thread has any thread-specific data, appropriate destructor
       functions shall be called in an unspecified order. Thread termination does not release any
       application  visible  process  resources,  including, but not limited to, mutexes and file
       descriptors, nor does it perform any process-level cleanup  actions,  including,  but  not
       limited to, calling any atexit() routines that may exist.

       An  implicit  call  to pthread_exit() is made when a thread other than the thread in which
       main() was first invoked returns from the start routine that was used to  create  it.  The
       function's return value shall serve as the thread's exit status.

       The  behavior of pthread_exit() is undefined if called from a cancellation cleanup handler
       or destructor function that was invoked as a result of either an implicit or explicit call
       to pthread_exit().

       After  a  thread  has  terminated,  the  result of access to local (auto) variables of the
       thread is undefined. Thus, references to local variables of the exiting thread should  not
       be used for the pthread_exit() value_ptr parameter value.

       The process shall exit with an exit status of 0 after the last thread has been terminated.
       The behavior shall be as if the implementation called  exit()  with  a  zero  argument  at
       thread termination time.

RETURN VALUE

       The pthread_exit() function cannot return to its caller.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       The  normal  mechanism by which a thread terminates is to return from the routine that was
       specified in the pthread_create()  call  that  started  it.  The  pthread_exit()  function
       provides  the  capability  for  a  thread to terminate without requiring a return from the
       start routine of that thread, thereby providing a function analogous to exit().

       Regardless of the method of thread termination, any  cancellation  cleanup  handlers  that
       have  been  pushed  and  not yet popped are executed, and the destructors for any existing
       thread-specific data are executed.  This  volume  of  IEEE Std 1003.1-2001  requires  that
       cancellation  cleanup  handlers  be  popped  and  called  in order. After all cancellation
       cleanup handlers have been executed, thread-specific data destructors are  called,  in  an
       unspecified  order,  for each item of thread-specific data that exists in the thread. This
       ordering is necessary because cancellation cleanup handlers may  rely  on  thread-specific
       data.

       As  the meaning of the status is determined by the application (except when the thread has
       been canceled, in which case it is PTHREAD_CANCELED), the implementation has no idea  what
       an illegal status value is, which is why no address error checking is done.

FUTURE DIRECTIONS

       None.

SEE ALSO

       exit()   ,   pthread_create()   ,   pthread_join()   ,  the  Base  Definitions  volume  of
       IEEE Std 1003.1-2001, <pthread.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2003  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003  by
       the  Institute  of  Electrical  and  Electronics Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE  and  The  Open  Group
       Standard,  the  original  IEEE  and  The  Open Group Standard is the referee document. The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .