MPI_Request_get_status sets \fIflag\fP=\fItrue\fP if the operation is complete or sets \fIflag\fP=\fIfalse\fP if it is not complete. If the operation is complete, it returns in \fIstatus\fP the request status. It does not deallocate or inactivate the request; a subsequent call to test, wait, or free should be executed with that request.
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If your application does not need to examine the \fIstatus\fP field, you can save resources by using the predefined constant MPI_STATUS_IGNORE as a special value for the \fIstatus\fP argument.
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.
