What is Elixir? Why learn it?

• General purpose language
• Functional
• Concurrent and Parallel
• Can cluster
• Easy to use
• Great tooling
• Emphasis on Dev Happiness

The Free Lunch is Over

• CPUs are no longer getting faster
• We're getting more of them instead
• Humans are bad at leveraging extra cores
• Maybe we should try different abstractions

The Bad Old Days

• Read concurrency book for your language
• Throw threads at the concurrency problem
• Throw locks at the race conditions from threads
• Throw a threadpool at the problem
• Sacrifice a goat
• I don't even understand these errors

Elixir is built on Erlang, so let's just take a little detour

Erlang is Revolutionary

• No more shared memory, no more threads, much fewer bugs
• Uses virtual "processes" (isolated units of code that are scheduled and run by the virtual machine)
• Processes communicate by sending messages asynchronously
• Processes can choose to block (or not) on incoming messages and react to them

Erlang's VM is revolutionary

• The BEAM (Erlang's VM) acts more like an OS
• Schedules processes, and balances them across cores
• Can use all cores to lower latency or use fewest possible cores to optimize power usage
• Has a soft-real time aspect
• Behaves well under high load
• Behaves well with few resources (min req are about 16MB storage, 20MB RAM, a few hundred MHz, and 32MB RAM)
• Libraries are called "Applications"
• Applications can depend on each other and are like small fleets of microservices in your VM

Erlang's Error Handling is revolutionary

• "Let it Crash" is a mantra about assertive coding
• You always code the happy path first
• You rarely write error handling code
• Applications use supervisors to launch processes
• Supervisors monitor a process and start and restart them according to a specified strategy
• Supervisors can be assembled into trees and can bubble up as different parts of your application are affected by the outage
• Crashes and Supervisors are a way your program returns to a "known good state", allowing your application to run well in the presence of bugs

Why hasn't Erlang eaten the world?

The Bad Old Days (Erlang)

• Learn a weird syntax/language
• Take days to set up project environment
• Look around github for libraries
• Consider if these problems are worse than the ones Erlang solves for you