The Semantics of Collective Communications

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The Semantics of Collective Communications

  semantics of collective collective, semantics of portabilitysafety collective, and portability collective, and deadlock

A correct, portable program must invoke collective communications so that deadlock will not occur, whether collective communications are synchronizing or not. The following examples illustrate dangerous use of collective routines.

Figure: A race condition causes non-deterministic matching of sends and receives. One cannot rely on synchronization from a broadcast to make the program deterministic.

Jack Dongarra
Fri Sep 1 06:16:55 EDT 1995