31 posts tagged with "go"

If you used sessions in Fiber v2, forget everything. Fiber v3 replaced the session system entirely. The store-based API is gone. Sessions are now middleware - you register them once and they are available on every request through the context.

This sounds like a small change. It is not. The new approach changes how you initialize sessions, how you access them in handlers, and how you handle the interaction between sessions and other middleware like CSRF. If you migrate without understanding the new model, you will spend hours debugging session data that silently disappears.

The typical file upload tutorial is five lines: parse the form, get the file, save it to disk. It works for a homework assignment. It fails the moment someone uploads a 2GB file, or a .exe renamed to .jpg, or a thousand files simultaneously.

Production file handling needs three things the tutorials skip: size limits that protect your server, type validation that goes beyond the extension, and storage patterns that do not block your event loop.

Most Go developers know that Go uses goroutines for concurrency. A single process handles thousands of connections by scheduling goroutines across OS threads. That is usually enough.

But Fiber has a trick that most Go frameworks do not: prefork mode. One line of config, and Fiber spawns multiple OS processes, each with its own event loop, all listening on the same port. It is the same pattern that Nginx and Node.js cluster mode use.

The surprise is not that Fiber supports this. The surprise is when it actually helps - and when it makes your app slower.