Introduction and use of goroutine in Go language

Introduction and use of goroutine in Go language

As an efficient, concise, and concurrent programming language, Go language supports coroutines as one of its features. Coroutine is a lightweight thread, which has the advantages of occupying less resources, low switching costs, and can efficiently implement concurrent operations. In the Go language, the use of coroutines is very convenient. This article will introduce the basic concepts and usage methods of coroutines, and how to implement efficient concurrent programming through coroutines.

The basic concept of coroutine

Coroutines are lightweight threads that are often referred to as user-mode threads in operating systems because they are implemented by user programs themselves rather than by the operating system kernel. Compared with traditional threads, coroutines have the following advantages:

• Occupies less resources: each coroutine only occupies very little stack space and some memory space, so a large number of coroutines can be started at the same time without exhausting system resources.

• Low switching cost: Coroutine switching only involves user mode stack switching and register saving and restoration, so it is much faster than thread context switching.

• Efficient concurrent operations: Coroutines can make good use of the multi-core processing capabilities of the CPU, and achieve efficient concurrent operations through the scheduling and switching of coroutines.

In the Go language, the implementation of coroutines is based on the Go runtime system. At program startup, the Go runtime system creates a main coroutine, which is responsible for program initialization and startup. During the running of the program, new coroutines can be created through the go keyword, for example:

goCopy code
func main() {
    go func() {
        // 协程代码
    }()
    // 主协程代码
}

In the above code, a new coroutine is created using the go keyword, and an anonymous function is executed in it. The main coroutine and the new coroutine can be executed in parallel without affecting each other.

How to use coroutines

In the Go language, using coroutines is very simple, just add the go keyword in front of the function or method that needs to be executed concurrently. For example, here's a simple coroutine example:

goCopy code
func main() {
    go func() {
        for i := 0; i < 10; i++ {
            fmt.Printf("协程中的计数器：%d\n", i)
        }
    }()
    for i := 0; i < 10; i++ {
        fmt.Printf("主协程中的计数器：%d\n", i)
    }
}

In the above example, a new coroutine is created with the go keyword and a simple for loop is executed in it. The main coroutine and the new coroutine can be executed in parallel, so the order of the output results is undefined.

In addition to using the go keyword to create a coroutine, the Go language also provides some other coroutine-related functions, such as:

• runtime.Gosched(): Actively give up the CPU time slice, so that other coroutines have a chance to run.

• sync.WaitGroup: Wait for a group of coroutines to finish executing before continuing.

Here is an example of a coroutine using sync.WaitGroup:

goCopy code
func main() {
    var wg sync.WaitGroup
    for i := 0; i < 10; i++ {
        wg.Add(1)
        go func(n int) {
            fmt.Printf("协程%d开始执行\n", n)
            time.Sleep(time.Second)
            fmt.Printf("协程%d执行完毕\n", n)
            wg.Done()
        }(i)
    }
    wg.Wait()
    fmt.Println("所有协程执行完毕")
}

In the above example, sync.WaitGroup is used to wait for all coroutines to finish executing. When creating a coroutine, the number of the coroutine is passed through the parameter n, which can conveniently output the execution status of each coroutine. After the execution of the coroutine is completed, mark the completion of the execution of the coroutine by wg.Done(), and finally wait for all the execution of the coroutine by wg.Wait().

Summarize

Coroutine is a very important concurrent programming mechanism in Go language. Its lightweight, low-cost, and high-efficiency features make it an ideal choice for achieving high concurrency. Through the go keyword and related coroutine functions, we can easily create and manage coroutines to achieve efficient concurrent programming. In actual development, it is necessary to use coroutines reasonably according to specific scenarios and requirements to improve the performance and maintainability of the program.

Author: Lu Zhengchao