NAME

       MPI_Waitany -  Waits for any specified MPI Request to complete

SYNOPSIS

       int MPI_Waitany(int count, MPI_Request array_of_requests[], int *indx,
                      MPI_Status *status)

INPUT PARAMETERS

       count  - list length (integer)
       array_of_requests
              - array of requests (array of handles)

OUTPUT PARAMETERS

       indx   -  index  of  handle  for  operation  that  completed (integer).  In the range 0 to
              count-1 .  In Fortran, the range is 1 to count .

       status - status object (Status).  May be MPI_STATUS_IGNORE .

NOTES

       If all of the requests are MPI_REQUEST_NULL , then indx is returned as MPI_UNDEFINED , and
       status is returned as an empty status.

       While  it  is  possible  to list a request handle more than once in the array_of_requests,
       such an action is considered  erroneous  and  may  cause  the  program  to  unexecpectedly
       terminate or produce incorrect results.

NOTES ON THE MPI_STATUS ARGUMENT

       The MPI_ERROR field of the status return is only set if the return from the MPI routine is
       MPI_ERR_IN_STATUS .  That error class is only returned by the routines that take an  array
       of  status  arguments ( MPI_Testall , MPI_Testsome , MPI_Waitall , and MPI_Waitsome ).  In
       all other cases, the value of the MPI_ERROR field in the status is unchanged.  See section
       3.2.5 in the MPI-1.1 specification for the exact text.

       For  send operations, the only use of status is for MPI_Test_cancelled or in the case that
       there is an  error  in  one  of  the  four  routines  that  may  return  the  error  class
       MPI_ERR_IN_STATUS  ,  in  which  case  the MPI_ERROR field of status will be set.  In that
       case, the value will be set  to  MPI_SUCCESS  for  any  send  or  receive  operation  that
       completed  successfully, or MPI_ERR_PENDING for any operation which has neither failed nor
       completed.

THREAD AND INTERRUPT SAFETY

       This routine is thread-safe.  This means that this routine may be safely used by  multiple
       threads  without the need for any user-provided thread locks.  However, the routine is not
       interrupt safe.  Typically, this is due to the use of memory allocation routines  such  as
       malloc or other non-MPICH runtime routines that are themselves not interrupt-safe.

NOTES FOR FORTRAN

       All  MPI  routines  in  Fortran  (except  for MPI_WTIME and MPI_WTICK ) have an additional
       argument ierr at the end of the argument list.  ierr  is  an  integer  and  has  the  same
       meaning  as  the  return  value  of  the  routine  in  C.   In  Fortran,  MPI routines are
       subroutines, and are invoked with the call statement.

       All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in Fortran.

ERRORS

       All MPI routines (except MPI_Wtime and MPI_Wtick ) return an error value;  C  routines  as
       the  value of the function and Fortran routines in the last argument.  Before the value is
       returned, the current MPI error handler is called.  By default, this error handler  aborts
       the  MPI  job.   The  error  handler  may  be  changed  with  MPI_Comm_set_errhandler (for
       communicators), MPI_File_set_errhandler (for files), and MPI_Win_set_errhandler  (for  RMA
       windows).   The  MPI-1  routine  MPI_Errhandler_set may be used but its use is deprecated.
       The predefined error handler MPI_ERRORS_RETURN may be used to cause  error  values  to  be
       returned.   Note  that  MPI  does  not  guarentee that an MPI program can continue past an
       error; however, MPI implementations will attempt to continue whenever possible.

       MPI_SUCCESS
              - No error; MPI routine completed successfully.
       MPI_ERR_REQUEST
              - Invalid MPI_Request .  Either null or, in the case of a MPI_Start or MPI_Startall
              , not a persistent request.
       MPI_ERR_ARG
              -  Invalid  argument.  Some argument is invalid and is not identified by a specific
              error class (e.g., MPI_ERR_RANK ).

                                            11/12/2016                             MPI_Waitany(3)