Fan-Out / Fan-In Parallelism

One message is broadcast to concurrent workers; a joiner collects all outputs once every source completes

Fan-Out / Fan-In Parallelism One message is broadcast to concurrent workers; a joiner collects all outputs once every source completes 01 / Input 02 / Fan-out 03 / Workers 04 / Fan-in 05 / Result Message · single input · 01 / Input Message single input Fan-Out · broadcast · 02 / Fan-out · 1 to N Fan-Out broadcast 1 to N Worker A · concurrent · 03 / Workers Worker A concurrent Worker B · concurrent · 03 / Workers Worker B concurrent Worker C · concurrent · 03 / Workers Worker C concurrent Fan-In Joiner · collect outputs · 04 / Fan-in · N to 1 Fan-In Joiner collect outputs N to 1 Result List · all outputs · 05 / Result Result List all outputs input copy copy copy output output output list[outputs] Legend primary data policy / PII async batch data store

Fan-Out

  • • A single message is copied to every worker
  • • Workers run concurrently, not in sequence
  • • Throughput scales with the number of workers

Fan-In

  • • The joiner collects one output per worker
  • • It fires only once every source completes
  • • Outputs are gathered into a single ordered list

The Barrier

  • • Fan-in is a synchronization barrier
  • • A slow worker holds the join until it finishes
  • • The result is deterministic regardless of finish order

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