Building Distributed Systems in Elixir: Part 7 - Worker Pool (From Scratch)

Hey everyone!

I’ve published Part 7 of the Building Distributed Systems in Elixir series, where we build core distributed systems and concurrency patterns from first principles using raw process primitives (spawn, send, receive) before reaching for OTP abstractions.

In this part, we explore Worker Pools and Bounded Concurrency

What’s covered:

• The Problem with Unbounded Concurrency: Why spawning 10,000 processes for heavy tasks leads to socket/database exhaustion and memory pressure.
• Demand-Driven / Pull-Based Distribution: How workers pull tasks when idle instead of pushing work blindly, implementing backpressure naturally.
• Atomic Completion & Availability: Combining job completion notifications and worker re-availability into a single message ({:available, worker_id, self(), job, result}) to prevent race conditions.
• Graceful Pool Lifecycle: Coordinating shutdown signals across a coordinator and worker pool without dangling processes.

Links:

• Read the article: Building Distributed Systems in Elixir: Part 7 — Worker Pool
• GitHub Repository: elixir-distributed-systems-lab

Feedback, thoughts, and discussions are always welcome!