It was 2AM. Most of the engineering team was asleep. The payment system was processing transactions normally. Then an alert fired. Duplicate charges were increasing. Not thousands. Not enough to immediately bring the entire system down. But enough to tell…
Three teams. One database. And almost every deployment required coordination between them. The system was technically working. Payments were processing. Settlement jobs were running. Ledger entries were being created. But engineering was becoming slower every month. A change that should…
The system was slow. But the dashboards looked healthy. We had CPU utilization under 50%. Memory was stable. Error rates were below 1%. Our monitoring alerts weren’t triggering. And yet customers were complaining about slowness. This was the contradiction we…
We had a system that looked healthy. Application CPU was reasonable. Memory was stable. The number of application instances had increased. The load balancer was distributing traffic normally. And yet response times kept getting worse. The first instinct was to…
We had a performance problem. One of the most frequently accessed pieces of data was being read far more often than it changed. The database was handling a large number of repeated reads. The obvious solution was caching. We introduced…
We had a performance problem. One part of the application was doing too much work during a synchronous request. The obvious solution was to move the work out of the request path. Instead of: we changed the flow to: The…
