What is a Process?

Fundamentals

• Unit of code execution on the BEAM
• They are cheap and fast to spin up/down
• Can easily have thousands of them running
• Each process has its own isolated memory space
  • Heap, stack and mailbox
• Communicate with one another via message passing
• Can think of them as independent programs/entities in your larger Application
  • They all just happen to be running on the same VM

What can you do with them?

• Storing state
  • Singleton processes can be useful for easily accessing data application wide
• Cron jobs
  • PromEx polls various BEAM internals and creates Prometheus metrics
• Supervising/monitoring other processes
  • Supervisors are also processes under the hood
• Initializing your application
  • Can run Ecto migrations in a GenServer prior to starting HTTP server
  • Hydrate cache (:persistent_term or :ets)
• Worker pools
• Effortless parallel processing via Task.async_stream/5

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