Advanced Language
Dive deep into Elixir concurrency with lightweight processes, GenServer, Supervisors, and the OTP framework. Build fault-tolerant, distributed systems.
Phase 3 introduces the runtime model that makes Elixir fundamentally different from most languages: many lightweight processes, message passing, and supervision. This is the point where you stop writing only functions and start designing resilient systems. These lessons build the mindset required for production-grade BEAM applications.
You will work through Recursion, Processes, GenServer, Supervisors, OTP Applications, ETS, and Task and Task.Supervisor.
Who this phase is for:
- Developers ready to reason about concurrency and process lifecycles.
- Engineers maintaining stateful or high-throughput Elixir services.
- Learners preparing for Phoenix internals, distributed systems, and observability.
What you should be able to do after this phase:
- Model problems as cooperating processes instead of shared mutable state.
- Choose between plain processes, GenServer, Task, and ETS based on behavior and constraints.
- Build supervision trees that recover automatically from crashes.
- Understand application boot order and runtime configuration boundaries.
Common pitfalls to watch for:
- Using GenServer for every problem instead of starting with pure functions.
- Storing too much mutable process state without clear ownership.
- Ignoring supervision strategy and shutdown semantics.
- Treating ETS as a default database replacement.
Before moving forward, make sure you can explain your process architecture out loud: which process owns what, how failures are handled, and how work is observed and retried.
Do not rush this phase. Most production incidents in Elixir systems trace back to unclear ownership, weak supervision design, or unbounded concurrency. Taking time here to model failure paths and recovery behavior pays off more than learning additional syntax.
Recursion
Master recursive thinking in Elixir -- base cases, tail call optimization, accumulator patterns, and when to use recursion vs Enum. With practical examples.
Processes
Understand Elixir's lightweight BEAM processes -- spawning, message passing, process linking, monitoring, and the foundations of concurrency in the Erlang VM.
GenServer
Learn Elixir's GenServer behaviour -- the OTP workhorse for building stateful, concurrent server processes. Covers callbacks, handle_call, handle_cast, and state management.
Supervisors
Build fault-tolerant Elixir systems with supervision trees, restart strategies, DynamicSupervisor, and the 'let it crash' philosophy. Essential OTP patterns.
OTP Applications
Understand the Elixir Application behaviour -- how to package, configure, and start supervised process trees using OTP. Covers app callbacks and runtime config.
ETS
Use ETS (Erlang Term Storage) for fast in-memory reads and concurrent shared state in Elixir. Covers table types, ownership, access modes, and production patterns.
Task and Task.Supervisor
Run concurrent work safely with Task and Task.Supervisor. Covers async/await, async_stream, cancellation, timeouts, and supervision-friendly background work.