Can you explain what epoll is and how it is used in Go for handling asynchronous events?

epoll is a mechanism in Linux for efficiently monitoring multiple file descriptors for input/output events (such as readiness for reading or writing). It allows an application not to block and not to poll each descriptor individually, but to receive notifications only about those where an event has occurred.

In Go, epoll is used within the runtime to implement non-blocking I/O and goroutine scheduling. Developers usually do not work directly with epoll, as the standard Go library (for example, the net package) already uses it under the hood for asynchronous network operations.

Example: when you run a server in Go and read data from a network connection, the runtime uses epoll to track socket readiness, so it does not block the goroutine and can switch efficiently between them.