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Subject: [OMPI users] Deadlock question
From: Gijsbert Wiesenekker (gijsbert.wiesenekker_at_[hidden])
Date: 2010-05-24 13:42:52

My MPI program consists of a number of processes that send 0 or more messages (using MPI_Isend) to 0 or more other processes. The processes check periodically if messages are available to be processed. It was running fine until I increased the message size, and I got deadlock problems. Googling learned I was running into a classic deadlock problem if (see for example The workarounds suggested like changing the order of MPI_Send and MPI_Recv do not work in my case, as it could be that one processor does not send any message at all to the other processes, so MPI_Recv would wait indefinitely.
Any suggestions on how to avoid deadlock in this case?