Let's talk about how to open multiple coroutines in Go language

In recent years, Go language has become one of the most popular programming languages ​​​​in the Internet field, and has excellent performance in the field of large-scale concurrency and high performance. When processing concurrent requests, opening multiple Go coroutines is an important way to improve system performance and response speed. So, how to open more Go coroutines?

The goroutine in the Go language is similar to a thread, but is more lightweight and efficient. Using goroutine, we can easily implement multi-tasking processing such as parallel computing and asynchronous IO.

First, let’s take a look at a simple example that shows how to use goroutine to handle multiple requests at the same time:

func main() {
    urls := []string{
        "http://www.google.com/",
        "http://www.apple.com/",
        "http://www.microsoft.com/",
        "http://www.facebook.com/",
    }

    for _, url := range urls {
        go request(url)
    }

    time.Sleep(time.Second)
}

func request(url string) {
    resp, err := http.Get(url)
    if err != nil {
        log.Fatal(err)
    }
    defer resp.Body.Close()

    body, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        log.Fatal(err)
    }

    fmt.Println(url, len(body))
}

The above code demonstrates how to fetch multiple websites concurrently Content, we use goroutine to handle each request simultaneously. However, in actual applications, if we use the above code directly, it may cause too many goroutines to be created, and may even cause the system to crash.

Therefore, we need to control the number of goroutines through optimization so that they can run within the system load tolerance.

First of all, we can control concurrency by limiting the number of goroutines. In the Go language, you can use waitgroup (a tool type in the sync package) to control the number of goroutines.

The following is a sample program:

func main() {
    urls := []string{
        "http://www.google.com/",
        "http://www.apple.com/",
        "http://www.microsoft.com/",
        "http://www.facebook.com/",
    }

    var wg sync.WaitGroup
    for _, url := range urls {
        wg.Add(1)
        go func(url string) {
            request(url)
            wg.Done()
        }(url)
    }

    wg.Wait()
}

func request(url string) {
    resp, err := http.Get(url)
    if err != nil {
        log.Fatal(err)
    }
    defer resp.Body.Close()

    body, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        log.Fatal(err)
    }

    fmt.Println(url, len(body))
}

In the above code, WaitGroup is used to control the number of goroutines. When a goroutine calls the waitgroup.Add(1) method, it means that a goroutine needs to be started to process the request; and when the goroutine finishes processing the request, it needs to call the waitgroup.Done() method, which means that a task has been completed.

In addition, we can also use the buffering mechanism of the go statement to control concurrency. The channel in the Go language can help us realize communication between goroutines and can be used to control the scheduling between goroutines. Caching channels can limit concurrency and thereby control the number of goroutines.

The following is a sample program:

func main() {
    urls := []string{
        "http://www.google.com/",
        "http://www.apple.com/",
        "http://www.microsoft.com/",
        "http://www.facebook.com/",
    }

    var wg sync.WaitGroup
    ch := make(chan string, 2)
    for _, url := range urls {
        ch <- url
        wg.Add(1)
        go func() {
            defer wg.Done()
            request(<-ch)
        }()
    }

    wg.Wait()
}

func request(url string) {
    resp, err := http.Get(url)
    if err != nil {
        log.Fatal(err)
    }
    defer resp.Body.Close()

    body, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        log.Fatal(err)
    }

    fmt.Println(url, len(body))
}

In the above code, we use a cached channel and create a channel with a capacity of 2 to limit the number of goroutines. At the same time, we use WaitGroup to wait for all goroutines to complete before the program exits.

In summary, to open more Go coroutines, you need to do the following:

1. Reasonably control the number of goroutines to avoid excessive system load caused by excessive goroutine creation.
2. Use mechanisms such as WaitGroup and channel to control concurrency and avoid competition and scheduling problems between goroutines.
3. Make reasonable use of system resources, process requests concurrently, and improve the response speed and performance of the system.

Of course, the above is just an idea and method of opening more Go coroutines. In actual production, we still need to optimize and design according to specific needs. I believe that with these basic knowledge, you will be able to better deal with the problem of multiple coroutines in Go language.

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