How does the Tokio runtime work internally?

Tokio is a cooperative task scheduler built around a work-stealing multi-threaded runtime that drives Futures using an executor.

Tokio operates as an async runtime that schedules tasks (Futures) onto worker threads. Each task is polled until it hits an await point. If it cannot progress, it yields control and registers a Waker. The runtime uses a work-stealing queue so idle threads can steal tasks from busy ones. I/O is handled via epoll/kqueue/IOCP depending on OS. This enables high concurrency without OS thread explosion.