Hi All,
A colleague recently asked a question that I wasn't able to answer
definitively. Is the following code guaranteed to make progress?
MPI_Barrier();
if rank == 1
create_file("test")
if rank == 0
while not_exists("test")
sleep(1);
That is, can rank 1 require rank 0 to make MPI calls after its return from
the barrier, in order for rank 1 to complete the barrier? If the code were
written as follows:
isend(..., other_rank, &req[0])
irecv(..., other_rank, &req[1])
waitall(2, req)
if rank == 1
create_file("test")
if rank == 0
while not_exists("test")
sleep(1);
I think it would clearly not guarantee progress since the send data can be
buffered. Is the same true for barrier?
Cheers,
~Jim.
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