Understand how threads and coroutines work in Golang

The working principle of threads and coroutines in Golang

In Go language (Golang), threads and coroutines are very important concepts, they are concurrent programming Basic components. Understanding how they work is important for developing efficient concurrent programs. This article will deeply explore the working principles of threads and coroutines in Golang, and use specific code examples to help readers better understand.

1. How threads work

In traditional operating systems, threads are the smallest execution units, and each thread has its own execution stack and register set. Threads are scheduled by the operating system kernel. A thread can be regarded as an independent execution sequence, and it can execute multiple tasks concurrently.

In Golang, there is a concept of Goroutine, which is similar to threads, but more lightweight. Goroutine is managed by the Go language runtime system, which wraps a function into a lightweight thread. Goroutines are executed concurrently, and multiple Goroutines can be run simultaneously in one thread. The Go language runtime determines how to schedule these Goroutines.

The following is a simple example that demonstrates how to create and use Goroutine in Golang:

package main

import (
    "fmt"
    "time"
)

func sayHello() {
    for i := 0; i < 5; i++ {
        fmt.Println("Hello")
        time.Sleep(1 * time.Second)
    }
}

func main() {
    go sayHello() // 启动一个新的Goroutine
    time.Sleep(3 * time.Second)
    fmt.Println("Main function")
}

In the above code, the sayHello() function will be wrapped as A Goroutine and executed in a new thread. In the main function, we start a new Goroutine by go sayHello(), and then the main function continues execution. After 3 seconds, the main function prints "Main function", and the function in Goroutine will continue to print "Hello" until the end of the loop.

2. Working principle of coroutine

In Golang, coroutine is a lightweight and efficient concurrent processing method. Unlike threads, coroutines are implemented in user space and are fully controlled by the developer. Coroutines can be seen as a subset of threads, whose switching is explicitly controlled by the programmer in the code.

Coroutines implement communication and synchronization in Golang by channel. Through channels, different coroutines can communicate with each other safely, avoiding the problem of concurrent access to shared memory. The following is an example of using channels for coroutine communication:

package main

import "fmt"

func sendData(ch chan int) {
    ch <- 1
}

func main() {
    ch := make(chan int)
    
    go sendData(ch)
    
    data := <-ch
    fmt.Println(data)
}

In the above code, we create a channel and send an integer to the channel in the sendData() function , and then receive the data through in the main function and print it out. Through the sending and receiving operations of the channel, coroutines can communicate safely, realizing collaboration and synchronization between coroutines.

Summary:

In Golang, threads and coroutines are important components to achieve concurrent programming. Threads are scheduled by the operating system kernel, and Goroutines are lightweight threads managed by the Go language runtime. Coroutines are a lightweight concurrency processing method that is controlled by developers. Through specific code examples, we can better understand the working principles of threads and coroutines in Golang. I hope this article can help readers better understand and apply concurrent programming.

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