Is golang single-process?

Golang is not a single process, but multi-threaded; the thread model of golang is the MPG model. Generally speaking, Go processes and kernel threads correspond to many-to-many, so first of all, it must be multi-threaded.

#golang is not a single process, but multi-threaded.

Golang has some so-called M ratio N model. N go routines can be created under M threads. Generally speaking, N is much larger than M. It is essentially a multi-threaded model, but the scheduling of coroutines is by Go's runtime decision emphasizes that developers should use channels for synchronization between coroutines.

As for threads, since the language level is not open, you can understand it as a multi-coroutine model. Several go routine can be created on one thread. Generally speaking, it will be created with the CPU The number of threads with the same number of cores is, of course, actually determined by runtime.

Regarding the scheduling of goroutine, this is actually constantly evolving. I will only talk about the GMP model. Goroutine runs on M threads, and the current P will be checked every time a task is executed. The executable queue on the (processor) contains executable goroutines. Once there is no executable goroutine on the current P, it will steal the goroutine in the executable queue of another P.

Theoretically, the creation of goroutine is only limited by memory. Generally speaking, the maximum is 2KB. For a thread with 2MB space, theoretically, it can easily reach 1,000. Of course, this is only an ideal situation, so the OS The number of threads will not increase as the number of goroutines created increases. Thread scheduling is relatively performance-intensive for Go. Frequent switching of schedules will only exist between goroutines, and threads will only maintain the same number of active threads as the number of CPUs.

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