Tell me about the Go scheduler and GMP model, as well as the work stealing mechanism.

The Go scheduler is based on the GMP model, where:

• G (goroutine) — a lightweight thread of execution.
• M (machine) — an OS system thread.
• P (processor) — a logical processor that connects G and M for execution.

In the Go runtime, there is a fixed number of P, which determines the maximum number of goroutines that can be executed simultaneously at the OS thread level.

Working mechanism:

• To execute a goroutine (G), it is assigned to a P.
• P is linked with an M (OS thread), and M executes G.
• When G blocks (for example, on a system call), M is released and can execute another G.

Work stealing is a load balancing mechanism among P. If one P's queue of goroutines is empty, it can 'steal' goroutines from another P's queue to evenly distribute work and improve thread utilization.

This approach allows efficient scaling of multithreaded programs, minimizing overhead from context switching and blocking.