Golang coroutines and async/await

Coroutines and async/await in Go are concurrency primitives, coroutines are lightweight execution threads, and async/await is syntactic sugar, allowing asynchronous code writing. Coroutines run in goroutines and are created using the go keyword. async/await uses the async keyword to define a coroutine, and uses the await keyword to pause the current coroutine and wait for other coroutines to complete. In practice, coroutines can be used to manage concurrent requests and avoid the overhead of creating and destroying coroutines for each request through the goroutine pool.

Comparison of coroutines and async/await in Go

In Go, coroutines and async/await are two concurrency primitives used for Write concurrent code.

Coroutine

Coroutine is a lightweight execution thread that allows us to execute code in multiple places at the same time. Coroutines run in goroutine, which is the Go language's implementation of user-mode threads.

The following is a code example for creating and using coroutines:

package main

import (
    "fmt"
    "sync"
)

func main() {
    var wg sync.WaitGroup

    for i := 0; i < 10; i++ {
        wg.Add(1)
        go func(i int) {
            fmt.Println(i)
            wg.Done()
        }(i)
    }

    wg.Wait()
}

async/await

async/await is a syntactic sugar that allows us to write asynchronous code, like It is executed just like in synchronous code. The async keyword is used to define a coroutine, while the await keyword is used to pause the current coroutine and wait for another coroutine to complete.

The following is a code example for creating and using async/await:

package main

import (
    "fmt"
    "sync"
)

func main() {
    var wg sync.WaitGroup

    wg.Add(1)
    result := asyncFunc()

    fmt.Println(result)

    wg.Wait()
}

func asyncFunc() int {
    return 42
}

Practical case

We can use coroutines and async/await to solve various concurrency problems. One of the most common uses is to manage concurrent requests through the use of goroutine pools.

The following is a Go code example that uses a goroutine pool to handle HTTP requests:

package main

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

var pool = sync.Pool{
    New: func() interface{} {
        return new(http.Request)
    },
}

func handler(w http.ResponseWriter, r *http.Request) {
    // 从池中检索请求
    req := pool.Get().(*http.Request)
    *req = *r

    // 处理请求

    // 将请求放回池中
    pool.Put(req)
}

func main() {
    http.HandleFunc("/", handler)
    http.ListenAndServe(":8080", nil)
}

By using a coroutine pool, we avoid the overhead of creating and destroying coroutines for each request. This can significantly improve the performance of handling concurrent requests.

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