On Mar 8, 2013, at 10:20 AM, George Bosilca <[email protected]> wrote:
>> If the app REQUEST_FREE'd a nonblocking send/receive, don't we block in
>> ompi_mpi_finalize() before the call to pml_base_close(), such that the PMLs
>> will be drained before we get to destroying the PMLs?
>
> We don't, as we have no way of knowing there are pending requests in the
> pipeline. There is a separation between who create the requests and who
> release them. They are created by the selected PML, and are destroyed by the
> base, after the selected PML has been turned off.
Here's an interesting case -- do you think that this is a valid MPI
application? And if it is, what is the expected behavior?
-----
#include <stdio.h>
#include <mpi.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#define SIZE 33554432
int main(int argc, char *argv[])
{
int i, rank;
char *buf;
MPI_Request req;
MPI_Init(NULL, NULL);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
buf = malloc(SIZE);
assert(buf);
memset(buf, rank, SIZE);
if (0 == rank) {
MPI_Isend(buf, SIZE, MPI_CHAR, 1, 123, MPI_COMM_WORLD, &req);
MPI_Request_free(&req);
} else if (1 == rank) {
MPI_Irecv(buf, SIZE, MPI_CHAR, 0, 123, MPI_COMM_WORLD, &req);
MPI_Request_free(&req);
}
MPI_Finalize();
if (1 == rank) {
for (i = 0; i < SIZE; ++i) {
assert(1 == buf[i]);
}
}
return 0;
}
-----
On the SVN trunk, this application will fail the assert(1 == buf[i]).
MPI-3 p360 shows a *similar* case, but it's not exactly the same (example 8.7
shows Request_free one *one* side, not *both* sides).
--
Jeff Squyres
[email protected]
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