Tell me about the goroutine scheduler in Go — the GMP model, what functions does it perform?

In Go, the goroutine scheduler is implemented based on the GMP model — an abbreviation for G (goroutine), M (machine), and P (processor).

• G — is the goroutine itself, a lightweight thread of execution.
• M — is the system thread (OS thread) on which goroutines run.
• P — is the logical processor that connects goroutines with threads.

P is limited to the number equal to GOMAXPROCS and manages the execution of goroutines, distributing them across available M. The GMP scheduler is responsible for switching between goroutines, load balancing, and efficient use of system threads.

Thus, the GMP model allows efficient management of a large number of goroutines over a limited number of OS threads, ensuring high concurrency and scalability.

Example: if you have 4 P (GOMAXPROCS=4), then up to 4 goroutines can run simultaneously on 4 OS threads, while the rest will wait their turn.