BY MICHEL PEREZELIXIR & PARALLEL PROGRAMMING

CONCURRENCY VS PARALLELISM

ELIXIR MECHANISMS

▸ PROCESS

▸ SPAWNING

▸ OTP

▸ GEN SERVER

▸ SUPERVISOR

▸ APPLICATION

PROCESSES

▸ Processes are the fundamental unit of concurrency in Elixir

▸ The Erlang VM supports up to 134 million of processes

▸ Lightweight processes

▸ Each actor is a process

▸ Each process performs a specific task

▸ Sends messages to communicate with the process

▸ The processes don’t share information

SPAWNING A PROCESS

PID

▸ Identifies a process in the EVM

▸ To send a message must point the pid

OTP

▸ The Erlang interpreter and compiler

▸ Erlang standard libraries

▸ Dialyzer, a static analysis tool

▸ Mnesia, a distributed database

▸ Erlang Term Storage (ETS), an in-memory database

▸ A debugger,

▸ An event tracer

▸ A release management tool

OTP BEHAVIOURS

▸ GenServer A behaviour module for implementing the server of a client-server relation.

▸ Supervisor A behaviour module for implementing supervision functionality

▸ Application A module for working with applications and defining application callbacks.

GEN SERVER - MODULE CALLS

▸ GenServer.start_link/3

▸ GenServer.call/3

▸ GenServer.cast/2

GEN SERVER - CALLBACKS

▸ init(args)

▸ handle_call(msg, {from, ref}, state}

▸ handle_cast(msg, state}

▸ handle_info(msg, state)

▸ terminate(reason, state)

▸ code_change(old_vsn, state, extra)

GENSERVER - INIT

▸ init(args)

▸ {:ok, state}

▸ {:ok, state, timeout}

▸ :ignore

▸ {:stop, reason}

GENSERVER - HANDLE CALL

▸ handle_call(msg, {from, ref},state)

▸ {:reply, reply, state}

▸ {:reply, reply, state, timeout}

▸ {:reply, reply, state, :hibernate}

▸ {:noreply, state}

▸ {:noreply, state, timeout}

▸ {:noreply, state, hibernate}

▸ {:stop, reason, reply, state}

▸ {:stop, reason, state}

GENSERVER - HANDLE CALL

▸ handle_cast(msg, state)

▸ {:noreply, state}

▸ {:noreply, state, timeout}

▸ {:noreply, state, :hibernate}

▸ {:stop, reason, state}

GENSERVER - HANDLE INFO - TERMINATE

▸ handle_info(msg, state)

▸ {:noreply, state}

▸ {:noreply, state, timeout}

▸ {:stop, reason, state}

▸ terminate(reason, state)

▸ :ok

GENSERVER - CODE CHANGE

▸ code_change(old_vsn, state, extra)

▸ {:ok, new_state}

▸ {:error, reason}

GENSERVER - EXAMPLE

SUPERVISOR

▸ Strategies

▸ :one_for_one

▸ :rest_for_one

▸ :one_for_all

▸ :simple_one_for_one

SUPERVISOR - EXAMPLE

APPLICATION

▸ Component implementing some specific functionality, that can be started and stopped as a unit, and which can be re-used in other systems

▸ Defines a supervision tree that must be started and stopped when the application starts and stops

▸ The start callback should return {:ok, pid}

APPLICATION - EXAMPLE

EXTREME

B1N1 N2

N3

N4

F1 N5

EXSTREME - CREATING A GRAPH

EXSTREME - RUNNING THE GRAPH

EXSTREME - NOTES

▸ https://github.com/mrkaspa/Exstreme

▸ Future

▸ Add Backpresure (GenStage)

▸ Supervising

▸ Remote nodes

THANKS!