Differences and applications of Golang coroutines and threads in concurrent programming

The difference between Golang coroutines and threads and their application in concurrent programming

Introduction:
In the field of concurrent programming, Golang is known for its excellent efficiency and Simplicity gets a lot of attention. Golang implements efficient concurrent programming through the mechanisms of Goroutine and Channel. This article will introduce the difference between Golang coroutines and threads, and give examples of how to apply coroutines in concurrent programming.

1. The difference between coroutines and threads
Coroutines and threads are two different ways to achieve concurrency. They differ in the following aspects.

1. Control of the scheduler:
   The coroutine is managed by the Golang runtime (Goroutine scheduler), and the scheduler is responsible for scheduling the execution of the coroutine on one or more threads. The Goroutine scheduler uses an algorithm called "work stealing", which can automatically balance workloads among different threads and improve concurrency performance. Threads are scheduled by the operating system kernel.
2. Memory requirements:
   Since threads are created and managed by the operating system kernel, each thread requires certain memory resources. Coroutines are created and managed by the Golang runtime scheduler, and they require only a small amount of memory space, usually only a few KB, which allows Golang to create millions of coroutines without running out of memory.
3. Overhead of creation and destruction:
   The creation and destruction of threads is very expensive, while the overhead of creation and destruction of coroutines is very small. This means that coroutines can be created and destroyed quickly in Golang, which is very important for handling a large number of concurrent tasks.
4. Concurrency model:
   Threads are a concurrency model based on shared memory. Memory is shared between multiple threads, and a lock mechanism is required to ensure data security. Coroutines communicate through channels, and share data by passing messages between coroutines, avoiding the complexity of using locks.

2. Application examples of coroutines

The following uses an example to illustrate how to use coroutines to implement concurrent programming in Golang.

package main

import (
    "fmt"
    "time"
)

func worker(id int, jobs <-chan int, results chan<- int) {
    for j := range jobs {
        fmt.Println("Worker", id, "started job", j)
        time.Sleep(time.Second) // 模拟任务处理
        fmt.Println("Worker", id, "finished job", j)
        results <- j * 2
    }
}

func main() {
    const numJobs = 5
    jobs := make(chan int, numJobs)
    results := make(chan int, numJobs)

    // 创建并启动多个协程
    for w := 1; w <= 3; w++ {
        go worker(w, jobs, results)
    }

    // 分发任务
    for j := 1; j <= numJobs; j++ {
        jobs <- j
    }
    close(jobs)

    // 获取任务结果
    for a := 1; a <= numJobs; a++ {
        <-results
    }
}

In the above example, we achieve the function of concurrently processing multiple tasks by creating multiple coroutines and communicating through channels. The main coroutine distributes tasks to the work coroutine, and the work coroutine executes the tasks and returns the results to the main coroutine.

Conclusion:
Golang’s coroutine and channel mechanism provide a simple and efficient solution for concurrent programming. Due to the lightweight and low resource consumption of coroutines and the efficient scheduling capabilities of the Goroutine scheduler, Golang can well support large-scale concurrent programming. In actual development, rational use of coroutines can greatly improve the concurrency performance of the program.

References:

1. https://tour.golang.org/concurrency/1
2. https://blog.golang.org/waza-talk -video
3. https://go.dev/play

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