SYNTAX

   C Syntax
          #include <mpi.h>

          int MPI_Startall(int count, MPI_Request array_of_requests[])

   Fortran Syntax
          USE MPI
          ! or the older form: INCLUDE 'mpif.h'
          MPI_STARTALL(COUNT, ARRAY_OF_REQUESTS, IERROR)
               INTEGER COUNT, ARRAY_OF_REQUESTS(*), IERROR

   Fortran 2008 Syntax
          USE mpi_f08
          MPI_Startall(count, array_of_requests, ierror)
               INTEGER, INTENT(IN) :: count
               TYPE(MPI_Request), INTENT(INOUT) :: array_of_requests(count)
               INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETER

       • count: List length (integer).

INPUT/OUTPUT PARAMETER

       • array_of_requests: Array of requests (array of handle).

OUTPUT PARAMETER

       • ierror: Fortran only: Error status (integer).

DESCRIPTION

       Starts  all  communications associated with requests in array_of_requests.  A call to MPI_Startall(count,
       array_of_requests) has the same effect as calls to MPI_Start (&array_of_requests[i]),  executed  for  i=0
       ,…, count-1, in some arbitrary order.

       A  communication  started  with  a  call to MPI_Start or MPI_Startall is completed by a call to MPI_Wait,
       MPI_Test,  or  one  of  the  derived  functions  MPI_Waitany,  MPI_Testany,   MPI_Waitall,   MPI_Testall,
       MPI_Waitsome,  MPI_Testsome  (these  are  described  in  Section  3.7.5  of  the  MPI Standard, “Multiple
       Completions”). The request becomes inactive after successful completion by such a call.  The  request  is
       not deallocated, and it can be activated anew by another MPI_Start or MPI_Startall call.

       A persistent request is deallocated by a call to MPI_Request_free (see Section 3.7.3 of the MPI Standard,
       “Communication Completion”).
       The call to MPI_Request_free can occur at any point in the program
       after the persistent request was created. However, the request will be
       deallocated only after it becomes inactive. Active receive requests
       should not be freed. Otherwise, it will not be possible to check that
       the receive has completed. It is preferable, in general, to free
       requests when they are inactive. If this rule is followed, then the
       persistent communication request functions will be invoked in a
       sequence of the form,

       Create (Start Complete)* Free

       where  *  indicates  zero  or  more  repetitions.  If  the  same  communication object is used in several
       concurrent threads, it is the user’s responsibility to coordinate calls so that the correct  sequence  is
       obeyed.

       A  send  operation  initiated  with  MPI_Start can be matched with any receive operation and, likewise, a
       receive operation initiated with MPI_Start can receive messages generated by any send operation.

ERRORS

       Almost all MPI routines return an error value; C routines as  the  return  result  of  the  function  and
       Fortran routines in the last argument.

       Before  the  error  value  is  returned,  the current MPI error handler associated with the communication
       object (e.g., communicator, window, file) is called.  If no communication object is associated  with  the
       MPI  call,  then  the call is considered attached to MPI_COMM_SELF and will call the associated MPI error
       handler.  When  MPI_COMM_SELF  is  not  initialized   (i.e.,   before   MPI_Init/MPI_Init_thread,   after
       MPI_Finalize,  or  when using the Sessions Model exclusively) the error raises the initial error handler.
       The initial error handler can be changed by calling MPI_Comm_set_errhandler on MPI_COMM_SELF  when  using
       the  World  model,  or the mpi_initial_errhandler CLI argument to mpiexec or info key to MPI_Comm_spawn/‐
       MPI_Comm_spawn_multiple.  If no other appropriate error handler has been set, then the  MPI_ERRORS_RETURN
       error  handler  is  called for MPI I/O functions and the MPI_ERRORS_ABORT error handler is called for all
       other MPI functions.

       Open MPI includes three predefined error handlers that can be used:

       • MPI_ERRORS_ARE_FATAL Causes the program to abort all connected MPI processes.

       • MPI_ERRORS_ABORT An error handler that can be invoked on a communicator, window, file, or session. When
         called on a communicator, it acts as if MPI_Abort was called on  that  communicator.  If  called  on  a
         window  or file, acts as if MPI_Abort was called on a communicator containing the group of processes in
         the corresponding window or file. If called on a session, aborts only the local process.

       • MPI_ERRORS_RETURN Returns an error code to the application.

       MPI applications can also implement their own error handlers by calling:

       • MPI_Comm_create_errhandler then MPI_Comm_set_errhandler

       • MPI_File_create_errhandler then MPI_File_set_errhandler

       • MPI_Session_create_errhandler then MPI_Session_set_errhandler or at MPI_Session_init

       • MPI_Win_create_errhandler then MPI_Win_set_errhandler

       Note that MPI does not guarantee that an MPI program can continue past an error.

       See the MPI man page for a full list of MPI error codes.

       See the Error Handling section of the MPI-3.1 standard for more information.

       SEE ALSO:

          • MPI_Bsend_init

          • MPI_Rsend_init

          • MPI_Send_init

          • MPI_Ssend_init

          • MPI_Recv_init

          • MPI_Start

          • MPI_Request_free

COPYRIGHT

       2003-2025, The Open MPI Community

                                                  Feb 17, 2025                                   MPI_STARTALL(3)