What type of multitasking does the Go scheduler implement?

The goroutine scheduler in the Go language implements cooperative multitasking with elements of preemption. A goroutine can be considered a lightweight thread that the scheduler switches between, allowing efficient use of system threads (M) and CPU cores.

The Go runtime uses an M:N model, where M is the number of system threads and N is the number of goroutines. The scheduler switches between goroutines during blocking operations or when explicitly calling the scheduler (e.g., runtime.Gosched()), which ensures cooperativeness. However, in some cases, the scheduler may preempt a goroutine to switch, bringing it closer to preemptive multitasking.

Thus, the goroutine scheduler is a hybrid of cooperative and preemptive multitasking, optimized for high performance and scalability.