Tell about the scheduler in Go — what is it for, what does it consist of?

The scheduler in Go is responsible for managing the execution of goroutines — lightweight threads that Go uses for concurrent execution of code.

It is needed for efficient distribution of goroutines across system threads (OS threads) to maximize CPU resource utilization while avoiding creating too many heavy threads.

The main components of the scheduler:

• G (Goroutine) — a structure describing a goroutine, its state, stack, and execution context.
• M (Machine) — a system thread of the OS on which goroutines are executed.
• P (Processor) — a logical processor that connects G and M. P contains a queue of goroutines ready to run.

The scheduler operates on the M:P:G model, where the number of P is limited (usually equal to the number of available CPUs), M are created and destroyed dynamically, and G are switched between M via P.

This allows Go to efficiently manage thousands of goroutines with minimal overhead compared to system threads.