gobench: a tool for comparing Go benchmark runs across branches

I’ve recently joined a new team that’s focused on performance, stability, and scalability – a change from my previous projects, where traffic was low enough that performance was rarely a concern. This codebase has already gone through multiple rounds of optimisation, so there’s no low-hanging fruit left. Any proposed change is inherently complex, and it’s rarely obvious whether a tweak will actually speed things up or slow them down. To measure the impact of our work, we’re leaning on the benchmarking tools in Go’s standard library. On one of my recent pull requests, I wrote a benchmark, and I pasted the output from two before/after runs. Paul improved this with a short shell script that ran multiple samples, and compared the results with the benchstat command. $ for N in {1..6}; do for C in 613000c fc12d4c; do echo $N: $C; git checkout -q $C && ./tool/go test -run=^X -bench=BenchmarkPostureAnalyzer ./control/posture/analysis/ | tee -a bench-$C.txt; done; done $ benchstat…