Solid Ground

ElixirDaze 2017

Video available at https://www.youtube.com/watch?v=5SbWapbXhKo

Transcript

1. Solid ground
   @sasajuric
   aircloak.com
   

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3. long-running system
   many tasks
   soft real-time
   finite time program
   all-or-nothing
   hard real-time
   

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4. NIFs
   

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5. scheduler scheduler scheduler scheduler
   BEAM
   CPU CPU CPU CPU
   

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6. frequent context switches
   

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7. t1
   t2
   t3
   t4
   t5
   10 s
   1 ms
   1 ms
   1 ms
   1 ms
   

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8. t1 t2 t3 t4 t5 t1
   BEAM scheduler
   

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9. t2 t3 t4 t5
   t1
   cooperative scheduler
   

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10. thread 1 thread n
    …
    long running task long running task
    blocked
    cooperative scheduler
    

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11. thread 1 thread n
    …
    long running task long running task
    not blocked :-)
    BEAM scheduler
    

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12. activities as runtime citizens
    

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13. send(pid, :please_stop)
    

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14. mref = Process.monitor(pid)
    send(pid, :please_stop)
    receive do
    {:DOWN, ^mref, :process, ^pid, _reason} ->
    :ok
    end
    

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15. mref = Process.monitor(pid)
    send(pid, :please_stop)
    receive do
    {:DOWN, ^mref, :process, ^pid, _reason} ->
    :ok
    after :timer.seconds(5) ->
    Process.exit(pid, :kill)
    receive do
    {:DOWN, ^mref, :process, ^pid, _reason} ->
    :ok
    end
    end
    

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16. task = Task.async(fn -> ... end)
    case Task.yield(task, :timer.seconds(5)) do
    {:ok, result} -> do_something(result)
    nil -> Task.shutdown(task, :brutal_kill)
    end
    

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17. shared-nothing concurrency
    

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18. Process
    heap
    resources
    

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19. process-owned “stuff” is released
    

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20. supervision tree
    

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21. system
    backend frontend
    chat history
    repo cache endpoint
    

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22. system
    backend
    chat history
    repo
    

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23. supervisor foundations
    frequent context switching
    activities as runtime citizens
    observable process termination
    stoppable processes
    shared-nothing concurrency
    

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24. runtime 

    guarantees
    syntax
    developer friendliness
    ecosystem
    

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25. Image credit
    Scales of Justice
    

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