In the previous post, I described an approximation of Heroku’s Bamboo routing stack, based on their blog posts. Hacker News, as usual, is outraged that the difficulty of building fast, reliable distributed systems could prevent Heroku from building a magically optimal architecture. Coda Hale quips:

Really enjoying @RapGenius’s latest mix tape, “I Have No Idea How Distributed Systems Work”.

Coda understands the implications of the CAP theorem. This job is too big for one computer–any routing system we design must be distributed. Distribution increases the probability of a failure, both in nodes and in the network itself. These failures are usually partial, and often take the form of degradation rather than the system failing as a whole. Two nodes may be unable to communicate with each other, though a client can see both. Nodes can lie to each other. Time can flow backwards.

For more on Timelike and routing simulation, check out part 2 of this article: everything fails all the time. There’s also more discussion on Reddit.

RapGenius is upset about Heroku’s routing infrastructure. RapGenius, like many web sites, uses Rails, and Rails is notoriously difficult to operate in a multithreaded environment. Heroku operates at large scale, and made engineering tradeoffs which gave rise to high latencies–latencies with adverse effects on customers. I’d like to explore why Heroku’s Bamboo architecture behaves this way, and help readers reason about their own network infrastructure.

To start off with, here’s a Rails server. Since we’re going to be discussing complex chains of network software, I’ll write it down as an s-expression:

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