Tell about how the Go scheduler (GMP model) works.

The Go scheduler is based on the GMP model — Goroutine, Machine, Processor.

• G (Goroutine) — a lightweight thread of execution created by the program.
• M (Machine) — a system thread of the OS that executes the goroutine.
• P (Processor) — a logical processor that connects G and M, managing the execution of goroutines.

Scheduler operation:

1. Each P has a queue of ready-to-run goroutines (G).
2. M is bound to a P and executes goroutines from its queue.
3. If a goroutine blocks (e.g., on a system call), M unbinds from P and looks for other work, and P is assigned to another M.
4. The scheduler balances the load among P, distributing goroutines for efficient use of OS threads.

This allows Go to efficiently manage thousands of goroutines with minimal overhead, providing concurrency and parallelism without explicit thread management.