MPI\_COMM\_ACCEPT(3) Open MPI MPI\_COMM\_ACCEPT(3)

MPI\_Comm\_accept — Establishes communication with a client.

# [SYNTAX](#SYNTAX)

## [C Syntax](#C_Syntax)

```
#include <mpi.h>
int MPI_Comm_accept(const char *port_name, MPI_Info info, int root, MPI_Comm comm, MPI_Comm *newcomm)
```

## [Fortran Syntax](#Fortran_Syntax)

```
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_COMM_ACCEPT(PORT_NAME, INFO, ROOT, COMM, NEWCOMM, IERROR)


    CHARACTER*(*)   PORT_NAME


    INTEGER     INFO, ROOT, COMM, NEWCOMM, IERROR
```

## [Fortran 2008 Syntax](#Fortran_2008_Syntax)

```
USE mpi_f08
MPI_Comm_accept(port_name, info, root, comm, newcomm, ierror)


    CHARACTER(LEN=*), INTENT(IN) :: port_name


    TYPE(MPI_Info), INTENT(IN) :: info


    INTEGER, INTENT(IN) :: root


    TYPE(MPI_Comm), INTENT(IN) :: comm


    TYPE(MPI_Comm), INTENT(OUT) :: newcomm


    INTEGER, OPTIONAL, INTENT(OUT) :: ierror
```

# [INPUT PARAMETERS](#INPUT_PARAMETERS)

- **port\_name** : Port name (string, used only on *root*).

[**info (Options given by root for the accept (handle, used only on)**](#info)

root). No options currently supported.

- **root** : Rank in *comm* of root node (integer).
- **comm** : Intracommunicator over which call is collective (handle).

# [OUTPUT PARAMETERS](#OUTPUT_PARAMETERS)

- **newcomm** : Intercommunicator with client as remote group (handle)
- **ierror** : Fortran only: Error status (integer).

# [DESCRIPTION](#DESCRIPTION)

MPI\_Comm\_accept establishes communication with a client. It is collective over the calling communicator. It returns an intercommunicator that allows communication with the client, after the client has connected with the MPI\_Comm\_accept function using the MPI\_Comm\_connect &lt;#mpi-comm-connect&gt; function. The port\_name must have been established through a call to MPI\_Open\_port &lt;#mpi-open-port&gt; on the root.

# [ERRORS](#ERRORS)

[Important](#Important)

In Open MPI, this function only works properly when the MPI job is launched via mpirun / mpiexec &lt;#man1-mpirun&gt;. Using this function in other run-time environments is currently unsupported, and may result in undefined behavior (e.g., the MPI job may hang).

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 &lt;#mpi-init&gt;/MPI\_Init\_thread &lt;#mpi-init-thread&gt;, after MPI\_Finalize &lt;#mpi-finalize&gt;, 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 &lt;#mpi-comm-set-errhandler&gt; 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 &lt;#mpi-comm-spawn&gt;/MPI\_Comm\_spawn\_multiple &lt;#mpi-comm-spawn-multiple&gt;. 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 &lt;#mpi-abort&gt; was called on that communicator. If called on a window or file, acts as if MPI\_Abort &lt;#mpi-abort&gt; 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 &lt;#mpi-comm-create-errhandler&gt; then MPI\_Comm\_set\_errhandler &lt;#mpi-comm-set-errhandler&gt;
- MPI\_File\_create\_errhandler &lt;#mpi-file-create-errhandler&gt; then MPI\_File\_set\_errhandler &lt;#mpi-file-set-errhandler&gt;
- MPI\_Session\_create\_errhandler &lt;#mpi-session-create-errhandler&gt; then MPI\_Session\_set\_errhandler &lt;#mpi-session-set-errhandler&gt; or at MPI\_Session\_init &lt;#mpi-session-init&gt;
- MPI\_Win\_create\_errhandler &lt;#mpi-win-create-errhandler&gt; then MPI\_Win\_set\_errhandler &lt;#mpi-win-set-errhandler&gt;

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

See the MPI man page &lt;#open-mpi&gt; for a full list of MPI error codes &lt;#open-mpi-errors&gt;.

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

**See also:**

•

MPI\_Comm\_connect &lt;#mpi-comm-connect&gt;

# [Copyright](#Copyright)

2003-2026, The Open MPI Community

October 30, 2026

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Document: MPI_Comm_accept(3) from openmpi-cuda-13.0 5.0.11-r1 (Chainguard OS)
Source: https://github.com/open-mpi/ompi