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MPI_Finalize - Terminates MPI execution environment.
#include <mpi.h>
int MPI_Finalize()
INCLUDE ’mpif.h’
MPI_FINALIZE(IERROR)
INTEGER IERROR
#include <mpi.h>
void Finalize()
- IERROR
- Fortran only: Error status (integer).
This
routine cleans up all MPI states. Once this routine is called, no MPI routine
(not even MPI_Init) may be called, except for MPI_Get_version, MPI_Initialized,
and MPI_Finalized. Unless there has been a call to MPI_Abort, you must ensure
that all pending communications involving a process are complete before
the process calls MPI_Finalize. If the call returns, each process may either
continue local computations or exit without participating in further communication
with other processes. At the moment when the last process calls MPI_Finalize,
all pending sends must be matched by a receive, and all pending receives
must be matched by a send.
MPI_Finalize is collective over all connected
processes. If no processes were spawned, accepted, or connected, then this
means it is collective over MPI_COMM_WORLD. Otherwise, it is collective
over the union of all processes that have been and continue to be connected.
All processes must call this routine before exiting. All processes
will still exist but may not make any further MPI calls. MPI_Finalize guarantees
that all local actions required by communications the user has completed
will, in fact, occur before it returns. However, MPI_Finalize guarantees
nothing about pending communications that have not been completed; completion
is ensured only by MPI_Wait, MPI_Test, or MPI_Request_free combined with
some other verification of completion.
For example, a successful return
from a blocking communication operation or from MPI_Wait or MPI_Test means
that the communication is completed by the user and the buffer can be reused,
but does not guarantee that the local process has no more work to do. Similarly,
a successful return from MPI_Request_free with a request handle generated
by an MPI_Isend nullifies the handle but does not guarantee that the operation
has completed. The MPI_Isend is complete only when a matching receive has
completed.
If you would like to cause actions to happen when a process
finishes, attach an attribute to MPI_COMM_SELF with a callback function.
Then, when MPI_Finalize is called, it will first execute the equivalent
of an MPI_Comm_free on MPI_COMM_SELF. This will cause the delete callback
function to be executed on all keys associated with MPI_COMM_SELF in an
arbitrary order. If no key has been attached to MPI_COMM_SELF, then no callback
is invoked. This freeing of MPI_COMM_SELF happens before any other parts
of MPI are affected. Calling MPI_Finalized will thus return "false" in any
of these callback functions. Once you have done this with MPI_COMM_SELF,
the results of MPI_Finalize are not specified.
Almost all MPI routines
return an error value; C routines as the value of the function and Fortran
routines in the last argument. C++ functions do not return errors. If the
default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error
the C++ exception mechanism will be used to throw an MPI::Exception object.
Before the error value is returned, the current MPI error handler is called.
By default, this error handler aborts the MPI job, except for I/O function
errors. The error handler may be changed with MPI_Comm_set_errhandler; 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.
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