Ubuntu Manpage: MPI_Startall - Starts a collection of requests.

Provided by: openmpi-doc_1.10.2-8ubuntu1_all

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[])

INPUT PARAMETER

       count     List length (integer).

INPUT/OUTPUT PARAMETER

       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.