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Using the above indexing feature, it is possible to use MPI to have offline-psana analyze events in parallel (this is useful for many, but not all, algorithms) by having different cores access different events (up to "thousands" of cores).  MPI can also work for online-psana from shared memory (an example script is here that was able to process 120Hz with 7MB/event on 3 machines (8 cores per machine)).  Online-psana from FFB can only be parallelized using MPI up to the number of DAQ "streams" (typically 6).  This  For an experiment that wants to use this parallelization: it's a good idea to increase the archiving rate of the slow EPICS data to the shot-rate.

This is some offline-psana sample code that sums a few images in parallel using the indexing feature:

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