How to write parallel HTTP requests in Go?

To perform parallel HTTP requests in Go, goroutines and sync.WaitGroup are typically used to wait for all requests to complete.

Example:

package main

import (
    "fmt"
    "net/http"
    "sync"
)

func fetch(url string, wg *sync.WaitGroup) {
    defer wg.Done()
    resp, err := http.Get(url)
    if err != nil {
        fmt.Printf("Request error to %s: %v\n", url, err)
        return
    }
    defer resp.Body.Close()
    fmt.Printf("Response from %s: %s\n", url, resp.Status)
}

func main() {
    urls := []string{
        "https://golang.org",
        "https://google.com",
        "https://github.com",
    }

    var wg sync.WaitGroup
    wg.Add(len(urls))

    for _, url := range urls {
        go fetch(url, &wg)
    }

    wg.Wait()
    fmt.Println("All requests completed")
}

In this example, a separate goroutine is launched for each URL to perform the HTTP request. WaitGroup ensures that the program waits for all requests to finish before exiting.