Detailed analysis of the coroutine scheduling model of Golang functions

Golang (also known as Go language) is a programming language based on C language. In recent years, it has attracted much attention and is widely used by developers. The design goal of Golang is to improve code readability, maintainability, concurrency and performance. Among them, Golang's concurrency is one of its biggest highlights. It uses the Goroutine computing model. This article will conduct a detailed analysis of the coroutine scheduling model in Golang.

1. Introduction to Goroutine

In the Golang language, coroutines are lightweight threads that run in the same address space and can be shared in the same process. data. Golang's coroutine is called Goroutine, which is managed by the runtime environment of the Go language. It can create a large number of coroutines in a very short time and can automatically schedule the execution of the coroutines.

2. Creation and destruction of Goroutine

In the Golang language, you can create a new coroutine through the go keyword and start the execution of a function:

go func () {
    // do something
}()

In this example, the execution of an anonymous function (func(){}) is started through the go keyword, and the execution of this function will be performed in a new coroutine. In Golang, the number of coroutines is managed by the runtime environment, which means we do not need to manually create or destroy a coroutine. When a coroutine completes execution, the runtime environment automatically destroys it.

3. Goroutine’s scheduling model

Golang’s coroutine adopts the M:N scheduling model. Where M represents the physical thread of the operating system, and N represents the number of Goroutines. The M thread in the M:N model coordinates the execution of N Goroutines through the scheduler. Golang's runtime environment will create enough M threads based on the actual situation of the system to ensure that multiple coroutines can be executed concurrently on different processors. This means that Golang's coroutines can achieve true concurrency instead of running alternately at different time slice intervals.

Golang’s scheduler has three types: system scheduler, user-level scheduler and network scheduler. The system scheduler is part of the Golang runtime environment. It is responsible for allocating coroutines to M threads and managing system-level scheduling. The user-level scheduler runs in the context of user code and is responsible for executing different Goroutines in turn within a period of time. The network scheduler is used to process I/O operations. It will transfer the I/O operations to a dedicated M thread so that it will not affect the I/O processing in the execution of other coroutines.

In the Goroutine scheduling model, Golang will perform preemptive scheduling when user code is executed. This means that Golang's scheduler will forcefully stop the executing Goroutine at some point and let another Goroutine waiting to be executed run. This scheduling mode can ensure fairness and prevent a certain coroutine from occupying CPU resources all the time.

4. Goroutine blocking and waking up

In Golang, coroutines can communicate through chan (channel). chan is a data structure that can communicate between different coroutines. It can block a coroutine until another coroutine sends a message to the chan (implemented by the <- symbol) or Receive messages (in the form chanName := <-chan). When a coroutine is blocked on chan, Golang's scheduler will stop the execution of the coroutine and transfer it to the wakeable queue. When the coroutine receiving chan receives the message and continues execution, Golang's scheduler will traverse the wakeable queue to obtain the coroutine and restore it to the execution queue.

5. Summary

Golang’s coroutine is one of its biggest highlights. It adopts the M:N scheduling model and can achieve very good performance in real concurrency scenarios. . At the same time, when using coroutines, you also need to pay attention to the communication methods between coroutines and the mechanism of blocking wake-up. When using coroutines, problems such as deadlock and starvation need to be avoided. Therefore, when using Golang coroutines, you need to fully understand the scheduling mechanism behind them to ensure the stability and performance of the code.

The above is the detailed content of Detailed analysis of the coroutine scheduling model of Golang functions. For more information, please follow other related articles on the PHP Chinese website!