18.2.473. MPIX_Comm_is_revoked — Open MPI 5.0.2 documentation

# 18.2.473. MPIX_Comm_is_revoked

MPIX_Comm_is_revoked - Test if a communicator is revoked.

This is part of the User Level Fault Mitigation ULFM extension.

## 18.2.473.1. SYNTAX

### 18.2.473.1.1. C Syntax

    #include <mpi.h>
    #include <mpi-ext.h>

    int MPIX_Comm_is_revoked(MPI_Comm comm, int *flag)

### 18.2.473.1.2. Fortran Syntax

    USE MPI
    USE MPI_EXT
    ! or the older form: INCLUDE 'mpif.h'

    MPIX_COMM_IS_REVOKED(COMM, FLAG, IERROR)
         INTEGER COMM, IERROR
         LOGICAL FLAG

### 18.2.473.1.3. Fortran 2008 Syntax

    USE mpi_f08
    USE mpi_ext_f08

    MPIX_Comm_is_revoked(comm, flag, ierror)
         TYPE(MPI_Comm), INTENT(IN) :: comm
         LOGICAL, INTENT(OUT) :: flag
         INTEGER, OPTIONAL, INTENT(OUT) :: ierror

## 18.2.473.2. INPUT PARAMETERS

- `comm`: Communicator (handle).

## 18.2.473.3. OUTPUT PARAMETERS

- `flag`: true if the communicator is revoked.

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

## 18.2.473.4. DESCRIPTION

Returns flag = true if the communicator associated with the handle comm is revoked at the calling process. It returns flag = false otherwise. The operation is local.

## 18.2.473.5. HOW CAN A COMMUNICATOR BECOME REVOKED

A communicator can become revoked when

1. the user calls the MPIX_Comm_revoke procedure on comm to revoke the communicator at the local process;

2. an MPI operation raised the error class MPIX_ERR_REVOKED because another process called the MPIX_Comm_revoke procedure on comm;

3. the communicator has the info key mpi_error_range set to group or universe, in which case the failure of any process in, respectively, the group of comm or the MPI universe caused an operation to raise an error of class MPIX_ERR_REVOKED.

## 18.2.473.6. REVOKE PROPAGATION AND ORDERING

Note that in a multithreaded application, a thread calling MPIX_Comm_is_revoked may return flag = true before the operation that raises the first exception of class MPIX_ERR_REVOKED has completed in a concurrent thread.

## 18.2.473.7. EFFECT OF A COMMUNICATOR REVOCATION

Once a communicator has been revoked at an MPI process, all subsequent non-local operations on that communicator (with some exceptions listed below), are considered local and must complete by raising an error of class MPIX_ERR_REVOKED at that MPI process.

## 18.2.473.8. OPERATIONS ON A REVOKED COMMUNICATOR

The following operations never raise an error of class MPIX_ERR_REVOKED, and complete with their normal semantics on a revoked communicator.

- MPIX_Comm_agree

- MPIX_Comm_iagree

- MPIX_Comm_shrink

- MPIX_Comm_ishrink

## 18.2.473.9. 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

- MPIX_Comm_revoke

- MPIX_Comm_agree

- MPIX_Comm_shrink