Reading Flame Graphs in Go

Mon, 01 Jan 0001 00:00:00 +0000

I nvisible performance bugs are the ones that scale with you. A function that takes 800 nanoseconds at 100 rows and 130 microseconds at 10,000 rows looks fine in every test you write on day one, and quietly becomes the reason a page hangs on day three hundred. You cannot fix what you cannot see — and a guess is not seeing.

This is a walkthrough of making one such bug visible: write a benchmark, capture a CPU profile, and read the flame graph until the cost stops being a mystery. The example is a real lookup from PayMeter, a small Go payments service, but the workflow is the same for anything.

Everything here uses only the standard toolchain — go test, go tool pprof, and Graphviz. No third-party profilers.

Profiling on Mike Mwita

Reading Flame Graphs in Go