18.2.285. MPI_Psend_init — Open MPI 5.0.0 documentation

# 18.2.285. MPI_Psend_init

MPI_Psend_init - Initializes a partitioned send.

## 18.2.285.1. SYNTAX

### 18.2.285.1.1. C Syntax

    #include <mpi.h>

    int MPI_Psend_init(const void *buf, int partitions, int count, MPI_Datatype datatype, int dest,
         int tag, MPI_Comm comm, MPI_Request *request)

### 18.2.285.1.2. Fortran Syntax

    USE MPI
    ! or the older form: INCLUDE 'mpif.h'
    MPI_PSEND_INIT(BUF, PARTITIONS, COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR)
         <type>  BUF(*)
         INTEGER PARTITIONS, COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR

### 18.2.285.1.3. Fortran 2008 Syntax

    USE mpi_f08
    MPI_Psend_init(buf, partitions, count, datatype, dest, tag, comm, request, ierror)
         TYPE(*), DIMENSION(..), INTENT(IN), ASYNCHRONOUS :: buf
         INTEGER, INTENT(IN) :: partitions, count, dest, tag
         TYPE(MPI_Datatype), INTENT(IN) :: datatype
         TYPE(MPI_Comm), INTENT(IN) :: comm
         TYPE(MPI_Request), INTENT(OUT) :: request
         INTEGER, OPTIONAL, INTENT(OUT) :: ierror

## 18.2.285.2. INPUT PARAMETERS

- `buf`: Initial address of send buffer (choice).

- `partitions`: Number of partitions (integer).

- `count`: Number of elements to be sent per partition (integer).

- `datatype`: Datatype of each element (handle).

- `dest`: Rank of source (integer).

- `tag`: Message tag (integer).

- `comm`: Communicator (handle).

## 18.2.285.3. OUTPUT PARAMETERS

- `request`: Communication request (handle).

- `ierror`: Fortran only: Error status (integer).

## 18.2.285.4. 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.

## 18.2.285.5. NOTE

The current implementation is an early prototype and is not fully compliant with the MPI-4.0 specification. Specifically this function and it’s counterpart (MPI_Precv_init) will block until the partitioned communication request is initialized on both ends. This behavior will be corrected in future versions.

See also

- MPI_Precv_init