Deep-dive developer posts on scaling, system design, OS internals, AI, and the edge cases that break production — every post ships with real, working code.
Start reading →// instance A, 10:00:00.100 wall clock
console.log(Date.now()); // 1735700400100
// instance B, same physical instant, clock running 400ms behind
console.log(Date.now()); // 1735700399700from: Clock Skew: Why Date.now() Lies Across Servers, and Hybrid Logical Clocks
Order B's event timestamp is earlier than order A's, even though A happened first on a different server. The servers' clocks drifted 400ms apart. Here's why wall-clock time can't order events across machines, and how Hybrid Logical Clocks fix it.
A hands-on review of Claude Code's subagent/Task tool after a week of real feature work with it — where delegating to a fresh-context agent genuinely pays off, where it just adds a round trip, and the failure mode worth knowing before you lean on it.
Running 3 instances of a cron worker means the nightly report runs 3 times. You don't need ZooKeeper or etcd to fix that — a lease row in the database you already have gets you correct leader election in about 30 lines.
The order list page loads fine with 5 orders in dev and falls over with 10,000 in production. Here's the ORM lazy-loading trap that causes it, how to see it in the query log, and the two real fixes: eager loading and batching.
RedBite's API starts throwing EMFILE at 3am, only under load, never in dev. Here's what a file descriptor actually is, why ulimit kills you in production and not locally, and the epoll-based fix that stops leaking them.
Save the order to Postgres, then publish to Kafka. The write between those two lines can fail and you'll never notice — until support tickets show orders that charged but never shipped. The outbox pattern fixes it.
