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MPI_Waitall.3.rst

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MPI_Waitall

:ref:`MPI_Waitall` - Waits for all given communications to complete.

SYNTAX

C Syntax

#include <mpi.h>

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

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_WAITALL(COUNT, ARRAY_OF_REQUESTS, ARRAY_OF_STATUSES, IERROR)
     INTEGER COUNT, ARRAY_OF_REQUESTS(*)
     INTEGER ARRAY_OF_STATUSES(MPI_STATUS_SIZE,*), IERROR

Fortran 2008 Syntax

USE mpi_f08
MPI_Waitall(count, array_of_requests, array_of_statuses, ierror)
     INTEGER, INTENT(IN) :: count
     TYPE(MPI_Request), INTENT(INOUT) :: array_of_requests(count)
     TYPE(MPI_Status) :: array_of_statuses(*)
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETERS

  • count: Lists length (integer).
  • array_of_requests: Array of requests (array of handles).

OUTPUT PARAMETERS

  • array_of_statuses: Array of status objects (array of status).
  • ierror: Fortran only: Error status (integer).

DESCRIPTION

Blocks until all communication operations associated with active handles in the list complete, and returns the status of all these operations (this includes the case where no handle in the list is active). Both arrays have the same number of valid entries. The ith entry in array_of_statuses is set to the return status of the ith operation. Requests that were created by nonblocking communication operations are deallocated, and the corresponding handles in the array are set to MPI_REQUEST_NULL. The list may contain null or inactive handles. The call sets to empty the status of each such entry.

The error-free execution of MPI_Waitall(count, array_of_requests, array_of_statuses) has the same effect as the execution of MPI_Wait(&array_of_request[i], &array_of_statuses[i]), for i=0,...,count-1, in some arbitrary order. :ref:`MPI_Waitall` with an array of length 1 is equivalent to :ref:`MPI_Wait`.

When one or more of the communications completed by a call to :ref:`MPI_Waitall` fail, it is desirable to return specific information on each communication. The function :ref:`MPI_Waitall` will return in such case the error code MPI_ERR_IN_STATUS and will set the error field of each status to a specific error code. This code will be MPI_SUCCESS if the specific communication completed; it will be another specific error code if it failed; or it can be MPI_ERR_PENDING if it has neither failed nor completed. The function :ref:`MPI_Waitall` will return MPI_SUCCESS if no request had an error, or will return another error code if it failed for other reasons (such as invalid arguments). In such cases, it will not update the error fields of the statuses.

If your application does not need to examine the array_of_statuses field, you can save resources by using the predefined constant MPI_STATUSES_IGNORE can be used as a special value for the array_of_statuses argument.

ERRORS

For each invocation of :ref:`MPI_Waitall`, if one or more requests generate an MPI error, only the first MPI request that caused an error will be passed to its corresponding error handler. No other error handlers will be invoked (even if multiple requests generated errors). However, all requests that generate an error will have a relevant error code set in the corresponding status.MPI_ERROR field (unless MPI_STATUSES_IGNORE was used).

If the invoked error handler allows :ref:`MPI_Waitall` to return to the caller, the value MPI_ERR_IN_STATUS will be returned in the C and Fortran bindings.

.. seealso::
   * :ref:`MPI_Comm_set_errhandler`
   * :ref:`MPI_File_set_errhandler`
   * :ref:`MPI_Test`
   * :ref:`MPI_Testall`
   * :ref:`MPI_Testany`
   * :ref:`MPI_Testsome`
   * :ref:`MPI_Wait`
   * :ref:`MPI_Waitany`
   * :ref:`MPI_Waitsome`
   * :ref:`MPI_Win_set_errhandler`