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NOTE: a complete working example of this pattern (for a vonHamos spectrometer) can be found here:  https://github.com/chrisvam/psana_cpo/tree/master/vonhamos

In the previous parallelization examples, all the cores have been analyzing data identically.  Another useful but somewhat more complex pattern is to have MPI clients intermittently sending updates to one master process that manages data visualization and storage.  This pattern is typically used only when running in real-time from shared memory where it is difficult to make sure that all nodes call Gather or Reduce the same number of times (collective MPI operations like gather/reduce cannot be used with shared memory! deadlocks can easily arise).  For real-time disk-based "smd" analysis Gather/Reduce can be used.

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