Code Review
Reviewing Python for the Mutable Default Argument and Its Cousins
The shared list default is the famous one, and reviewers catch it on sight. The module level cache, the captured dict and the class attribute list are its…
Rohit Bhadani
I write about why software breaks and how people figure it out. Founder of Krova Cloud, building isolated microVMs on our own hypervisor. Years of Shopify theme work and shared hosting before that. If I have not reproduced it, I do not publish it.
Opinion
Estimates Are Not Commitments, and the Confusion Costs You
The estimate became a date, the date became a promise, and the promise taught engineers to pad, hide and cut corners.
Bug Hunt
The Cron That Skipped Every Month With Thirty One Days
The monthly report ran in some months and silently vanished in others, and the pattern was the calendar. A day arithmetic bug that only fires on the 31st is…
Error Autopsy
The Hydration Mismatch That Only Happened With an Ad Blocker
Support got screenshots of a broken header that no one could reproduce, until someone enabled an ad blocker. The client side DOM was being edited after…
Deep Dive
How Cloudflare Freed 100 TB by Deleting 64 Bytes at a Time
Five successive changes to a Rust cache entry took it from 953 bytes to 420 across 250 billion entries, and made lookups 19 percent faster rather than slower.
DevOps
The Word Doing All the Work in the AWS Data Loss Notice
AWS confirmed in September that data held exclusively in me-south-1 and mec1-az2 cannot be restored. Multi-AZ worked as designed.
Deep Dive
What a Database Actually Does When It Says Committed
The commit returns before the data is on the platter, and the gap between the log write and the flush is where durability lives, and where one setting…
Performance
The Third Party Script That Held the Main Thread Hostage
First paint waited on a vendor's deploy, because a synchronous tag manager script blocked the parser, and its long tasks queued every interaction behind…
Deep Dive
The Checkpoint Storm That Spiked Latency Every Few Minutes
Latency was fine, then terrible, then fine, on a rhythm of a few minutes, with no traffic rhythm to match. The period was the checkpoint interval, and the…
DevOps
The Failover That Promoted a Replica Hours Behind
The primary died and the replica took over in seconds, which is what the dashboard promised. The last three hours of writes were not there, because the…
Deep Dive
Why Adding One Server Moved Everyone's Cache
The cache was sharded by modulo, so the twelfth server rehashed every key, and the whole cluster went cold at once, and the database took the entire load in…
Tooling
Reading a HAR File Like a Flight Recorder
The browser recorded the entire incident, every request, every wait, every byte, before anyone knew there was one.