Author, The Complete Guide to Rails Performance. Co-maintainer of Puma. https://t.co/7B62wCK5qT (he/him)
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Feb 14, 2022 • 5 tweets • 1 min read
ActiveRecord performance puzzle: "SELECT <long-list-of-columns>" sometimes takes ~10-40x longer than "SELECT *", randomly. Issue is not at the database, where query is consistently <1ms. Issue reproduces in Rails console.
Basically run it 10x in the console and you'll see 1ms, 1ms, 1ms, 40ms, 1ms, 1ms, 40ms, 1ms, 1ms.
May 7, 2021 • 4 tweets • 1 min read
In a production environment, the optimal Puma configuration for 80% of apps is probably 4 workers, 5 threads on a 4vCPU machine with ~8GB of memory.
and yes, in k8s, this would be per-pod, horizontal pod autoscaler running on top of that with request queue time as the metric
Mar 12, 2021 • 6 tweets • 2 min read
I put in a big PR to speed up my client's most important background job by 10-30%. This was really important because it generates 90%+ of their load. Let me walk you through it, commit-by-commit. (1/6)
First, we write some simple scripts to benchmark and profile the code in question. I used Benchmark from stdlib here because running this code once takes about 40 seconds. Note the warmup and use of transactions. github.com/WikiEducationF… (2/6)
Apr 12, 2020 • 7 tweets • 2 min read
All of these qualities are not ineffable. We can (and should) quantify them: LOC, dependency LOC, hours spent fixing bugs and dealing w/incidents, and server costs. Your customer has requirements for these. You don't need to magically guess them on their behalf: you have to ask.
Craftsperson attitude is about delivering the highest possible software quality regardless of customer requirement. This is wrong. You should deliver what the customer requires: no more and no less.
