NAME¶
MPI_Startall - Starts a collection of requests.
SYNTAX¶
C Syntax¶
#include <mpi.h>
int MPI_Startall(int count, MPI_Request *array_of_requests)
Fortran Syntax¶
INCLUDE 'mpif.h'
MPI_STARTALL( COUNT, ARRAY_OF_REQUESTS, IERROR)
INTEGER COUNT, ARRAY_OF_REQUESTS(*), IERROR
C++ Syntax¶
#include <mpi.h>
static void Prequest::Startall(int count, Prequest array_of_requests[])
- count
- List length (integer).
- array_of_requests
- Array of requests (array of handle).
OUTPUT PARAMETER¶
- IERROR
- Fortran only: Error status (integer).
DESCRIPTION¶
Starts all communications associated with requests in array_of_requests. A call
to MPI_Startall(count, array_of_requests) has the same effect as calls to
MPI_Start (&array_of_requests[i]), executed for i=0 ,..., count-1, in some
arbitrary order.
A communication started with a call to MPI_Start or MPI_Startall is completed by
a call to MPI_Wait, MPI_Test, or one of the derived functions MPI_Waitany,
MPI_Testany, MPI_Waitall, MPI_Testall, MPI_Waitsome, MPI_Testsome (these are
described in Section 3.7.5 of the MPI-1 Standard, "Multiple
Completions"). The request becomes inactive after successful completion
by such a call. The request is not deallocated, and it can be activated anew
by another MPI_Start or MPI_Startall call.
A persistent request is deallocated by a call to MPI_Request_free (see Section
3.7.3 of the MPI-1 Standard, "Communication Completion").
The call to MPI_Request_free can occur at any point in the program after the
persistent request was created. However, the request will be deallocated only
after it becomes inactive. Active receive requests should not be freed.
Otherwise, it will not be possible to check that the receive has completed. It
is preferable, in general, to free requests when they are inactive. If this
rule is followed, then the persistent communication request functions will be
invoked in a sequence of the form,
Create (Start Complete)* Free
where * indicates zero or more repetitions. If the same communication object is
used in several concurrent threads, it is the user's responsibility to
coordinate calls so that the correct sequence is obeyed.
A send operation initiated with MPI_Start can be matched with any receive
operation and, likewise, a receive operation initiated with MPI_Start can
receive messages generated by any send operation.
ERRORS¶
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.
SEE ALSO¶
MPI_Bsend_init
MPI_Rsend_init
MPI_Send_init
MPI_Ssend_init
MPI_Recv_init
MPI_Start
MPI_Request_free