MPIX_Comm_shrink(3) Manual Page

This collective operation creates a new intra- or intercommunicator newcomm from the intra- or intercommunicator comm, respectively, by excluding the group of failed MPI processes as agreed upon during the operation. The groups of newcomm must include every MPI process that returns from MPIX_Comm_shrink, and it must exclude every MPI process whose failure caused an operation on comm to raise an MPI error of class MPI_ERR_PROC_FAILED or MPI_ERR_PROC_FAILED_PENDING at a member of the groups of newcomm, before that member initiated MPIX_Comm_shrink. This call is semantically equivalent to an MPI_Comm_split operation that would succeed despite failures, where members of the groups of newcomm participate with the same color and a key equal to their rank incomm.

This function never raises an error of class MPI_ERR_PROC_FAILED or MPI_ERR_REVOKED. The defined semantics of MPIX_Comm_shrink are maintained when comm is revoked, or when the group of comm contains failed MPI processes

This routine is part of the MPIX extension to the MPI standard. It may become part of the standard in the future, in which its signature will change to the MPI prefix.

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.

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.

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 communicators), '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 predefined 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.