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41 posts so far.
How a Redis Cache Key Missing One Field Leaked Client Data Across Tenants for 72 Hours
A SaaS platform cached API responses by resource ID alone — when two tenants happened to share the same integer ID, one client spent three days reading another's confidential records.
How a Redis Connection Leak Crashed Our AWS ECS Cluster at 3AM
A Redis client spawned inside getServerSideProps accumulated 8,847 open connections over six hours, OOM-killed every ECS task, and took the service down for 47 minutes before we found the root cause.
How a Missing useCallback Triggered 10,000 API Requests Per Minute in Production
A React search component's unstable function reference created an infinite useEffect loop that sent 10,400 req/min to our backend until the rate-limiter started blacklisting our own users.
The Shared State Trap: How a FastAPI 'Optimisation' Leaked User Data
We replaced Flask's request-scoped g with a plain dict during migration. Under async concurrency, that dict silently served one tenant's data to a completely different user.
The Invisible Bottleneck: How One Sync Call Froze Our Node.js API
A single fs.readFileSync buried in a utility function seemed harmless in development — in production under real traffic, it silently froze every request in the system for 700ms at a time.
We Killed the PHP Monolith. It Took 18 Months and One Client's Data.
What looked like a clean strangler-fig migration turned into 18 months of session bridges, soft-delete mismatches, and hard lessons about the implicit contracts hiding inside every legacy codebase.
The Friday Deploy That Taught Me to Respect PostgreSQL
A four-line SQL query worked perfectly in development — in production, with 8 million rows, it held the database hostage for 47 minutes and took down an entire SaaS platform on a Friday afternoon.
We Deployed on a Friday. Here's What Happened Next.
A production deploy at 4:30 PM on a Friday turned a routine release into a 6-hour incident — and permanently changed how I think about automation and discipline.
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