The baking-events execution flow in one diagram (with sequence chart)
Short version: baking-events needs almost no tuning at small and medium scale — the point where it starts to hurt is much further out than most people assume. Full measurements below.
The first thing was to collapse the variables. We were changing config and upgrading the version at the same time, and afterwards nobody could say which change caused what. We rolled back to moving one variable at a time, re-ran three times, and only then did the curve settle. Tedious, but not skippable.
# Load test: do not jump straight to the max concurrency. # Ramp it up, otherwise you miss the knee. for c in 50 100 200 400 800; do wrk -t8 -c$c -d60s --latency http://127.0.0.1:8080/api/feed sleep 20 done
What genuinely surprised me was the tail. The average looked great while P99 jumped by an order of magnitude past some threshold. The cause was not baking-events itself but our upstream connection reuse — the load test traffic was too clean and hid the long-tail requests.
Worth noting: the official docs do cover this, just in a very inconspicuous spot. I only found it reading the source comments, where the author explains the reasoning — roughly "so that it degrades into predictable behaviour in extreme cases".
We also fixed monitoring along the way: replaced average-based alerts with percentiles and split them per endpoint. False alerts dropped by about seventy percent and the on-call rotation visibly cheered up.