What connection pools do
The pool is a small set of reusable database connections. Requests can only query while holding one of those glowing slots.
Interactive Systems Explainers
Database Connection Pool Playground
See how limited database connections create bottlenecks, queues, and latency spikes.
Related Concepts
Key Observations
What to Notice
Why requests wait
When every slot is occupied, new requests stack in front of the pool. The app may look alive while work is blocked.
Why more workers can stall
Workers help until the pool is saturated. After that, extra workers mostly create more blocked requests waiting together.
How long queries block the system
Long queries hold slots longer. That lowers connection turnover and makes everyone behind them feel the delay.
Interactive Systems Explainers