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Subject: [OMPI users] Interaction of MPI_Send and MPI_Barrier
From: Shaun Jackman (sjackman_at_[hidden])
Date: 2009-07-23 17:02:51


Two processes run the following program:

request = MPI_Irecv
MPI_Send (to the other process)
flag = MPI_Test(request)

Without the barrier, there's a race and MPI_Test may or may not return
true, indicating whether the message has been received. With the
barrier, is it guaranteed that the message will have been received,
and MPI_Test will return true?