There is a line of code almost all of us have written at some point that looks completely harmless: preg_match('/^(\w+\s?)*$/', $text), or its JavaScript cousin /^([a-z]+\s?)+$/. With a ten-character ...
You open a website in Madrid and the packets reach a server in Virginia passing through a dozen networks owned by different companies that compete with each other and share no boss. There is no centra...
Two people type into the same paragraph at the same time, each from a different city, and neither loses what they wrote. Behind that everyday scene lies a fairly serious computer science problem: how ...
For decades, talking to a disk from a program meant one request after another: the process called into the kernel, the kernel did the work, the process waited and called again. Every one of those syst...
There is an idea that sounds like a contradiction in any modern database engine: to write fast, you must avoid modifying what is already written. LSM engines (short for Log-Structured Merge) take that...
There is a layer of software that has changed, over the last few years, the way Linux servers are observed and protected, and it almost never makes the headline: eBPF. Its starting idea is easy to sta...
For decades, a web connection leaned on an inseparable pair: TCP to open a reliable channel and HTTP to request and deliver resources. That scheme worked well until the web stopped being a collection ...
Every time you log into a web application, a small object with three sections decides whether your next request is yours or an impostor’s. It is called a JSON Web Token (JWT), and its success co...
When you type a word in a search engine, millions of pages that contain it reappear within milliseconds. It is tempting to imagine that engine “reading” your documents on the fly and compa...
Every time you open an HTTPS page, the same little miracle repeats itself in a few milliseconds: two machines that have never met must agree on a shared secret while a third party listens to the whole...
A bank cannot charge the same payroll twice. An airline must not sell the last seat to two passengers at the same time. Currency exchange bets, shopping carts, like counters: behind all of these there...