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  - count (non-negative integer)

INPUT/OUTPUT PARAMETERS

       array_of_requests
              - array of requests (handle)

OUTPUT PARAMETERS

       indx   - index of handle for operation that completed (integer)
       status - status object (Status)

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 guarantee 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_ARG
              -  Invalid  argument.  Some argument is invalid and is not identified by a specific
              error class (e.g., MPI_ERR_RANK ).
       MPI_ERR_COUNT
              - Invalid count argument.  Count arguments must be non-negative; a count of zero is
              often valid.
       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_OTHER
              - Other error; use MPI_Error_string to get more information about this error code.

                                            2/22/2022                              MPI_Waitany(3)