2026-04-07 · Go

Use pprof to find a Go bottleneck

From a slow endpoint to a readable flame graph in under thirty minutes.

Introduction

A practical tour of net/http/pprof: CPU profiles, heap snapshots, and reading the top frames without guessing. The example ends by fixing a quadratic loop hidden inside JSON marshalling.

What usually goes wrong

Teams that skip this step tend to share three failure modes:

  • Optimizing a number nobody agreed to move.
  • Copying a setup from a project with different constraints.
  • Deferring the decision until it is expensive to reverse.

How to approach it

  1. State the problem in one sentence, in the words your users would use.
  2. Pick a signal you can measure weekly, not just at launch.
  3. Timebox a small trial; a two-day spike beats a two-week debate.

Wrap-up

If Go taught us anything, it is that boring consistency beats clever one-offs. Bring the lessons back to your team before they fossilize into folklore.