golang makes multiple requests

In modern application development, sending multiple requests has become a common requirement. Go language (Golang), as an efficient and fast language, naturally provides a variety of methods to issue multiple requests at the same time. This article will cover a few different ways to make multiple requests in Golang.

1. Basic method: for loop

The most basic way to issue multiple requests is to use a loop statement. In a loop, we can create multiple HTTP clients, each client is responsible for sending a request and returning its response. The advantages of this method are that it is simple and easy to understand, the code is easy to write, and the readability is relatively good.

The sample code is as follows:

package main

import (
    "fmt"
    "io/ioutil"
    "net/http"
)

func main() {
    urls := []string{"https://www.google.com", "https://www.baidu.com", "https://www.yahoo.com"}

    for _, url := range urls {
        resp, err := http.Get(url)

        if err != nil {
            panic(err)
        }

        defer resp.Body.Close()

        body, err := ioutil.ReadAll(resp.Body)

        if err != nil {
            panic(err)
        }

        fmt.Printf("Response from %s:
", url)
        fmt.Println(string(body))
    }
}

This code loops through three URLs and outputs each response to the console. For a small number of requests, this approach is feasible, but with a large number of requests, this approach can consume a lot of time and resources.

2. Use Goroutines

In order to improve performance, you can use Goroutines to complete multiple requests concurrently. Goroutines are lightweight threads in Go programs that allow us to run multiple tasks at the same time without blocking the execution of the main program. Using Goroutines can greatly improve application performance.

The sample code is as follows:

package main

import (
    "fmt"
    "io/ioutil"
    "net/http"
)

func main() {
    urls := []string{"https://www.google.com", "https://www.baidu.com", "https://www.yahoo.com"}

    for _, url := range urls {
        go func(url string) {
            resp, err := http.Get(url)

            if err != nil {
                panic(err)
            }

            defer resp.Body.Close()

            body, err := ioutil.ReadAll(resp.Body)

            if err != nil {
                panic(err)
            }

            fmt.Printf("Response from %s:
", url)
            fmt.Println(string(body))
        }(url)
    }
}

This code uses Goroutines to make requests to three URLs concurrently. In this way, requests can be made simultaneously, significantly reducing program execution time. However, unlike for loops, we need to pay attention to how goroutines access shared data and how to avoid race conditions when dealing with concurrency.

3. Using Channels

Golang provides another mechanism to coordinate communication between concurrent tasks: Channels. Channels allow communication between Goroutines based on message passing, which is ideal for sharing data between multiple tasks. Through Channels, we can ensure synchronization between Goroutines, thus avoiding race conditions.

The sample code is as follows:

package main

import (
    "fmt"
    "io/ioutil"
    "net/http"
)

func worker(url string, c chan string) {
    resp, err := http.Get(url)

    if err != nil {
        panic(err)
    }

    defer resp.Body.Close()

    body, err := ioutil.ReadAll(resp.Body)

    if err != nil {
        panic(err)
    }

    c <- string(body)
}

func main() {
    urls := []string{"https://www.google.com", "https://www.baidu.com", "https://www.yahoo.com"}

    c := make(chan string)

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

    for i := 0; i < len(urls); i++ {
        fmt.Printf("Response from %s:
", urls[i])
        fmt.Println(<-c)
    }
}

This code uses Channels to pass response data from Goroutines to the main program. We define a function called worker that receives a URL and a channel parameter c. In the function, we make an HTTP request to the specified URL and send its response to the channel as a string type. The main function outputs the response data by reading the response from the channel. In this process, we use Channels to manage communication between concurrent tasks.

4. Using concurrent request libraries

In the Go developer community, there are many libraries created for sending concurrent requests. These libraries help us easily write efficient concurrent code by simplifying the complexity of sending requests and managing concurrency. The following are several commonly used concurrent request libraries:

1. [Curl](https://github.com/go-curl/curl): This library provides a CURL library binding for the Go language , supports bulk messaging, sessions, HTTP/2, etc.
2. [Goroutines Pool](https://github.com/ivpusic/grpool): This library provides a Goroutine pool for sending high concurrent requests.
3. [Fasthttp](https://github.com/valyala/fasthttp): Fasthttp is a fast HTTP client and server library that can be used in high-concurrency scenarios.
4. [Gorequest](https://github.com/parnurzeal/gorequest): This library can help us quickly create HTTP requests and supports concurrent requests.

These libraries provide some convenient and easy-to-use APIs to help us create efficient concurrent code. When using these libraries, you need to pay attention to the correct use of the API and be familiar with the basics of concurrency processing.

Conclusion

This article introduces several methods of sending multiple requests in Go language. The choice of the above methods depends on the specific needs and scenarios. We need to choose appropriate methods and tools based on the actual situation. Regardless of the approach, we should follow best practices to create efficient, stable concurrent code, which can save time and resources and improve application performance.

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