Tim Johns' Blog

I work at Tiller Money , where last week, Ed, our marketing lead, asked me to write up just a couple of short paragraphs for " What is one thing (big or small) you wish you could teach your college-age self about money? " True to form, when I have something to say, nobody can get me to shut up, so I wrote up what was probably WAY more than he needed, and trimmed it down for that post. The result was a concise, honest, earnest bit that fit nicely into that larger piece. The trimmed-down version lost a little of my tongue-in-cheek whiney vibe (which -- perhaps secondary to excessive verbosity -- is also my style). I don't think that style is the best fit for our company blog, but is ABSOLUTELY a good fit for my PERSONAL blog. So here you go; the long form, in all it's whiney, parenthetical, not-terribly- concise glory! Ed asked -- what is one thing (big or small) you wish you could teach your college-age self about money? Well, I was lucky; I happen to

Seeing High CPU Steal on AWS Burstable Instance Types? At Tiller , we were, too. We have some backend systems that process data offline, using a job processing system that we’ve set up in a one layer of an AWS OpsWorks stack, using a node-based Agenda job processors running on t2.small instances. We’ve been having some subtle problems for a while, that we finally reached a point we could no longer ignore, and so we looked in deeper. The symptoms were that, after a while, an instance in that layer becomes busy enough to start missing deadlines and generating significant numbers of errors. We noticed a high amount of CPU Steal on those instances, at those times, and initially thought we might be suffering from the ‘noisy neighbor’ problem. Turns out it wasn’t a noisy neighbor: it was us.  Spoiler alert: our choice of instance type and job processor algorithm weren’t really a good match. This outstanding blog post by Leonid Mamchenkov was a great help in figuring this out,