NOTE
Multithreaded Blocking I/O Server
A thread-per-connection blocking server, its simplicity, and the need for bounded resources and modern virtual-thread context.
This is a historical learning note and may contain outdated or incomplete understanding.
A traditional BIO server accepts a socket and assigns connection work to another thread. This isolates blocking reads from the accept loop and keeps the code sequential.
With platform threads, use a bounded executor or explicit connection limit; an unbounded thread/queue strategy can fail under slow-client or overload conditions.
Virtual threads can simplify the same architecture at much higher concurrency, but resource limits still belong around connections, requests, DB calls, and other scarce dependencies.