MPIX_Comm_agree(3) MPI MPIX_Comm_agree(3)
NAME
MPIX_Comm_agree - Performs agreement operation on comm
SYNOPSIS
int MPIX_Comm_agree(MPI_Comm comm, int *flag)
INPUT PARAMETERS
comm - communicator (handle)
OUTPUT PARAMETERS
flag - new communicator (logical)
NOTES
The purpose of this collective communication is to agree on the integer
value flag and on the group of failed processes in comm.
On completion, all non-failed MPI processes have agreed to set the out-
put integer value of flag to the result of a bitwise AND operation over
the contributed input values of flag. If comm is an intercommunicator,
the value of flagis a bitwise AND operation over the values contributed
by the remote group.
When an MPI process fails before contributing to the operation, the
flag is computed ignoring its contribution, and MPIX_Comm_agree raises
an error of class MPI_ERR_PROC_FAILED. However, if all MPI processes
have acknowledged this failure priorto the call to MPIX_Comm_agree,
using MPIX_Comm_failure_ack, the error related to this failure is not
raised. When an error of class MPI_ERR_PROC_FAILED is raised, it is
consistently raised at allMPI processes, in both the local and remote
groups (if applicable).
After MPIX_Comm_agree raised an error of class MPI_ERR_PROC_FAILED, a
subse-quent call to MPIX_Comm_failure_ack on comm acknowledges the
failure of every MPI process that didn t contribute to the computation
offlag.
THREAD AND INTERRUPT SAFETY
This routine is thread-safe. This means that this routine may be
safely used by multiple threads without the need for any user-provided
thread locks. However, the routine is not interrupt safe. Typically,
this is due to the use of memory allocation routines such as malloc or
other non-MPICH runtime routines that are themselves not interrupt-
safe.
NOTES FOR FORTRAN
All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK ) have
an additional argument ierr at the end of the argument list. ierr is
an integer and has the same meaning as the return value of the routine
in C. In Fortran, MPI routines are subroutines, and are invoked with
the call statement.
All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in
Fortran.
ERRORS
All MPI routines (except MPI_Wtime and MPI_Wtick ) return an error
value; C routines as the value of the function and Fortran routines in
the last argument. Before the value is returned, the current MPI error
handler is called. By default, this error handler aborts the MPI job.
The error handler may be changed with MPI_Comm_set_errhandler (for com-
municators), MPI_File_set_errhandler (for files), and
MPI_Win_set_errhandler (for RMA windows). The MPI-1 routine
MPI_Errhandler_set may be used but its use is deprecated. The prede-
fined error handler MPI_ERRORS_RETURN may be used to cause error values
to be returned. Note that MPI does not guarantee that an MPI program
can continue past an error; however, MPI implementations will attempt
to continue whenever possible.
MPI_SUCCESS
- No error; MPI routine completed successfully.
MPI_ERR_ARG
- Invalid argument. Some argument is invalid and is not identi-
fied by a specific error class (e.g., MPI_ERR_RANK ).
MPI_ERR_COMM
- Invalid communicator. A common error is to use a null commu-
nicator in a call (not even allowed in MPI_Comm_rank ).
MPI_ERR_OTHER
- Other error; use MPI_Error_string to get more information
about this error code.
2/22/2022 MPIX_Comm_agree(3)
mpi 4.0.1 - Generated Thu Mar 31 08:48:18 CDT 2022