The hidden trap in simple queues (and how to fix it)

Published 11 months ago • 1 min read

Peter Mbanugo

pmbanugo.me

Hello Reader,

I've published a new blog post and it is about QUEUES.

You have used a queue today. In fact, you have probably used one dozens of times before lunch.

Whether it is Spotify loading songs in order, your server processing background jobs, or just waiting at the supermarket checkout, the FIFO (First-In, First-Out) queue is the invisible engine that keeps modern systems running smoothly.

You have used Kafka, RabbitMQ, and likely a Queue data types in your language's standard library.

But have you ever tried to build one from scratch?

In my latest article, Write Your Own FIFO Queue: An Essential Data Structure for Modern Systems, we peel back the layers of abstraction to build a high-performance queue.

Here is what is inside:

1. The "Creeping Index" Trap

If you implement a queue using a standard array, you will hit a nasty bug: your queue can run out of space even when it is half empty. I explain why this happens and how it breaks your system.

2. The Solution

We solve the memory problem using a Ring Buffer. I’ll show you the logic (and the maths) behind wrapping your data around the end of an array to achieve infinite scrolling within a fixed memory block.

3. Arrays vs. Linked Lists

"Why not just use a Linked List?" It is a common question. I dive into how your CPU cache works and why hopping around memory with a Linked List can be significantly slower than sticking to a contiguous array.

Even if you don't write Zig, the logic here applies to Rust, C, TypeScript, or any language where performance matters.

Enjoy it and let me know if you find it useful

Read now

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