An introduction to how we used the Elixir Task module to increase the performance of our application. Covers what Elixir Tasks are, how to use them and cases where it's not so good. Code for demo are here: https://github.com/jgmchan/elixir_task_demo

1. Increasing performance with Elixir
Tasks
Jeffrey Chan
Alembic
Twitter: @jgmchan
Github: https://github.com/jgmchan
Email: jgmchan@gmail.com

2. Background
✤ Client product - Places students into classes
✤ Algorithm time took > 4 minutes (sometimes 10)
✤ Sequential number crunching to work out best
solution
✤ Users were willing to wait but…
✤ Cloud service LB has a hard limit of 230s

3. Option 1
✤ Scale vertically
✤ Stronger CPU
✤ But already had the
largest CPU’s

4. Option 2
✤ Scale Horizontally
✤ Efficiently use more of
the CPU’s available
✤ Elixir Tasks

5. Option 3 (Bonus)
✤ Change the algorithm
✤ Actually the “real” correct solution
✤ Can’t get faster than not doing it

6. ElixirTask Module
✤ Module for spawning and awaiting tasks
✤ https://hexdocs.pm/elixir/Task.html
✤ Really easy to use (Erlang)

7. How they work
✤ Spawn separate Erlang processes to do work
✤ Wait for child process to send a message back with
result
✤ Processes are linked

8. How they work
✤ Single Process
✤ Input →⛏ → ⛏ → ⛏ → 💰

9. How they work
✤ With Tasks
✤ P1: Input →🤰 → ☕ → 😴 → 📞 →💰
⇣
P2: ⇢ 👶 →⛏ → ⇡
⇣
P3: ⇢ 👶 → ⛏→ ⇡
⇣
P4: ⇢ 👶 →⛏ → ⇡

10. Pre-requisites
✤ Tasks are short lived - usually isolated (no
communication)
✤ Pure functions are best

11. Demo!

12. Massive Performance Improvement
😎

13. Massive Performance Improvement
May as well use it everywhere
🤑 🤑 🤑

14. Massive Performance Improvement
Or is it?

15. A Better Demo

16. Limitations
✤ Number of CPU’s (can use multiple machines)
✤ BEAM overhead of switching tasks

17. Conclusion
✤ Task module can be very handy and easy to parallelise
your program
✤ Can use all the cores available in your machine (and
other machines)
✤ Not the answer to all problems
✤ Always measure!

18. Thanks!