NAME

       MPI_Waitall -  Waits for all given MPI Requests to complete

SYNOPSIS

       int MPI_Waitall(int count, MPI_Request array_of_requests[],
                      MPI_Status array_of_statuses[])

INPUT PARAMETERS

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

OUTPUT PARAMETERS

       array_of_statuses
              - array of status objects (array of Statuses).  May be MPI_STATUSES_IGNORE .

NOTES

       If  one  or  more of the requests completes with an error, MPI_ERR_IN_STATUS is returned.  An error value
       will be present is elements of array_of_status associated with the  requests.   Likewise,  the  MPI_ERROR
       field  in  the  status  elements  associated  with  requests  that  have  successfully  completed will be
       MPI_SUCCESS .  Finally, those requests that have not completed will have a value of MPI_ERR_PENDING .

       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 ).
       MPI_ERR_IN_STATUS
              -  The  actual  error value is in the MPI_Status argument.  This error class is returned only from
              the multiple-completion routines ( MPI_Testall  ,  MPI_Testany  ,  MPI_Testsome  ,  MPI_Waitall  ,
              MPI_Waitany  ,  and MPI_Waitsome ).  The field MPI_ERROR in the status argument contains the error
              value or MPI_SUCCESS (no error and complete) or MPI_ERR_PENDING to indicate that the  request  has
              not  completed.   The  MPI  Standard  does  not specify what the result of the multiple completion
              routines is when an error occurs.  For example, in an MPI_WAITALL , does the routine wait for  all
              requests  to  either  fail  or complete, or does it return immediately (with the MPI definition of
              immediately, which means independent of actions of other MPI processes)?  MPICH has chosen to make
              the return immediate (alternately, local in MPI terms), and to use the error class MPI_ERR_PENDING
              (introduced in MPI 1.1) to indicate which requests have not completed.  In most  cases,  only  one
              request  with  an  error  will  be  detected  in  each  call to an MPI routine that tests multiple
              requests.  The requests that have not been processed (because an  error  occured  in  one  of  the
              requests) will have their MPI_ERROR field marked with MPI_ERR_PENDING .

                                                   11/12/2016                                     MPI_Waitall(3)