https://semikolan.me/tags/debugging/ Recent content in debugging on semikolan Hugo en Mon, 27 Jul 2026 21:19:11 +0530 https://semikolan.me/blog/the-profiler-is-always-right/ Fri, 03 Apr 2026 00:00:00 +0000 https://semikolan.me/blog/the-profiler-is-always-right/ <p>I keep a mental list of times I was certain I knew where the time was going, ran a profiler to confirm it, and got humbled. The list is long. The profiler&rsquo;s record against me is perfect.</p> <h2 id="the-bottleneck-was-never-where-i-looked">The bottleneck was never where I looked <a class="anchor" href="#the-bottleneck-was-never-where-i-looked" aria-label="Link to this section">#</a></h2> <p>I&rsquo;d stare at the gnarly nested loop, the obvious <code>O(n²)</code>, and optimize it for an afternoon. The profiler would then point, flatly, at a <code>json.Marshal</code> call in the logging path that ran on every request. The scary algorithm ran twice a day. The boring serialization ran a million times an hour.</p>