A guilty pleasure of mine is the pursuit of perfection. It is certainly a vice in most contexts, but there are some problems whose solutions demand a measure of perfection. These are problems that I will refer to as “5-9 problems”: problems whose solutions need five 9’s (or more) in some dimension. Usually, those nines are correctness of some kind, but they can also be availability or for some systems, speed.
As you build a computer system, little things start to show up: maybe that database query is awkward for the feature you are building, or you find your server getting bogged down transferring gigabytes of data in hexadecimal ASCII, or your app translates itself to Japanese on the fly for hundreds of thousands of separate users. These are places where your abstractions are misaligned - your app would be quantitatively better if it had a better DB schema, a way to transfer binary data, or native internationalization for your Japanese users. Each of these misalignments carries a cost.
A lot of ink is spent on the “monoliths vs. microservices” debate, but the real issue behind this debate is about whether distributed system architecture is worth the developer time and cost overheads. By thinking about the real operational considerations of our systems, we can get some insight into whether we actually need distributed systems for most things.
We have all gotten so familiar with virtualization and abstractions between our software and the servers that run it. These days, “serverless” computing is all the rage, and even “bare metal” is a class of virtual machine. However, every piece of software runs on a server. Since we now live in a world of virtualization, most of these servers are a lot bigger and a lot cheaper than we actually think.