如何使用中间件管理 golang 中的并发请求，提升吞吐量？

// 示例中间件来限制并发请求
func RequestLimiter(next http.Handler) http.Handler {
    sema := make(chan struct{}, 10) // 允许 10 个并发请求

    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        sema <- struct{}{}        // 获取信号量
        defer func() { <-sema }() // 释放信号量
        next.ServeHTTP(w, r)
    })
}

// 示例中间件来队列和调度请求
func RequestScheduler(next http.Handler) http.Handler {
    queue := make(chan *http.Request)

    go func() {
        for r := range queue {
            next.ServeHTTP(r.ResponseWriter, r)
        }
    }()

    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        queue <- r
    })
}

// 示例中间件来添加请求超时机制
func RequestTimeout(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        ctx, cancel := context.WithTimeout(r.Context(), 10*time.Second)
        defer cancel()

        req := r.Clone(ctx)
        next.ServeHTTP(w, req)
    })
}

func main() {
    mux := http.NewServeMux()
    mux.HandleFunc("/api/v1/users", HandleUsers)

    // 添加并行请求限制
    mux.Use(RequestLimiter(50))

    // 启动服务器，监听 8080 端口
    log.Fatal(http.ListenAndServe(":8080", mux))
}