SYNTAX

   C Syntax
          #include <mpi.h>

          int MPI_Isendrecv(const void *sendbuf, int sendcount, MPI_Datatype sendtype,
              int dest, int sendtag, void *recvbuf, int recvcount,
              MPI_Datatype recvtype, int source, int recvtag,
              MPI_Comm comm, MPI_Request *request)

   Fortran Syntax
          USE MPI
          ! or the older form: INCLUDE 'mpif.h'
          MPI_ISENDRECV(SENDBUF, SENDCOUNT, SENDTYPE, DEST, SENDTAG,
                  RECVBUF, RECVCOUNT, RECVTYPE, SOURCE, RECVTAG, COMM,
                  REQUEST, IERROR)
              <type>    SENDBUF(*), RECVBUF(*)
              INTEGER    SENDCOUNT, SENDTYPE, DEST, SENDTAG
              INTEGER    RECVCOUNT, RECVTYPE, SOURCE, RECVTAG, COMM
              INTEGER    REQUEST, IERROR

   Fortran 2008 Syntax
          USE mpi_f08
          MPI_Isendrecv(sendbuf, sendcount, sendtype, dest, sendtag, recvbuf,
                  recvcount, recvtype, source, recvtag, comm, request, ierror)
              TYPE(*), DIMENSION(..), INTENT(IN) :: sendbuf
              TYPE(*), DIMENSION(..) :: recvbuf
              INTEGER, INTENT(IN) :: sendcount, dest, sendtag, recvcount, source,
              recvtag
              TYPE(MPI_Datatype), INTENT(IN) :: sendtype, recvtype
              TYPE(MPI_Comm), INTENT(IN) :: comm
              TYPE(MPI_Request) :: request
              INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETERS

       • sendbuf: Initial address of send buffer (choice).

       • sendcount: Number of elements to send (integer).

       • sendtype: Type of elements in send buffer (handle).

       • dest: Rank of destination (integer).

       • sendtag: Send tag (integer).

       • recvcount: Maximum number of elements to receive (integer).

       • recvtype: Type of elements in receive buffer (handle).

       • source: Rank of source (integer).

       • recvtag: Receive tag (integer).

       • comm: Communicator (handle).

OUTPUT PARAMETERS

       • recvbuf: Initial address of receive buffer (choice).

       • request: Communication request (handle).

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

DESCRIPTION

       The  non-blocking send-receive operations combine in one call the sending of a message to one destination
       and the receiving of another message, from another process. The two (source and destination) are possibly
       the same. This operation is useful for executing a shift operation  across  a  chain  of  processes.  The
       send-receive  operation  can  be  used  in  conjunction  with  the  functions  described  in the “Process
       Topologies” chapter of the MPI Standard in order to perform shifts on various logical topologies.

       A message sent by a send-receive operation can be received by a regular receive operation or probed by  a
       probe operation; a send-receive operation can receive a message sent by a regular send operation.

       MPI_Isendrecv  executes  a  non-blocking  send  and receive operation. Both send and receive use the same
       communicator, but possibly different tags.  The send buffer and receive buffers must be disjoint, and may
       have different lengths and datatypes.

       A non-blocking send-receive  request  can  be  determined  to  be  completed  by  calling  the  MPI_Wait,
       MPI_Waitany, MPI_Test, or MPI_Testany with the request returned by this function.

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_Isendrecv_replace

          • MPI_Sendrecv

          • MPI_Sendrecv_replace

COPYRIGHT

       2003-2025, The Open MPI Community

                                                  Feb 17, 2025                                  MPI_ISENDRECV(3)