Backend & systems·Concurrency and coordination
you keep a fixed set of threads and hand them tasks, instead of spawning a new thread for every request.
Thread pool
Also calledworker pool, executor
A bounded set of reusable workers fed from a queue. It caps concurrency, which is the point: unbounded thread creation converts a traffic spike into memory exhaustion and context-switch thrash. Sizing is workload-dependent — roughly core count for CPU-bound work, much higher for I/O-bound — and a blocking call inside a pool sized for CPU work will stall everything.