How does Go WebSocket achieve load balancing?

Implementing WebSocket load balancing in Go includes: creating a WebSocket handler, upgrading HTTP requests and handling connections; creating a polling load balancer responsible for allocating requests to servers; integrating the load balancer into the handler, and polling options are available server.

How Go WebSocket implements load balancing

Load balancing is a means of distributing requests to multiple servers to improve Availability and performance. Load balancing is especially important in WebSocket connections because it prevents individual servers from being overloaded.

Here is a step-by-step guide to implementing WebSocket load balancing using Go:

1. Create a WebSocket handler

First, you need to create a WebSocket handler Requested program. This program can handle connection requests and message exchanges.

import "net/http"

// 升级 HTTP 请求并处理 WebSocket 连接
func WsUpgrade(res http.ResponseWriter, req *http.Request) {
    conn, err := websocket.Upgrade(res, req, nil, 1024, 1024)
    if err != nil {
        http.Error(res, "Could not establish websocket.", http.StatusBadRequest)
        return
    }
    defer conn.Close()

    // 处理 WebSocket 消息
    for {
        // 读取并处理传入的消息
        _, message, err := conn.ReadMessage()
        if err != nil {
            break
        }

        // 向客户端发送消息
        conn.WriteMessage(websocket.TextMessage, []byte("消息已收到："+string(message)))
    }
}

2. Create a load balancer

To create a load balancer, you need to use a round robin algorithm to decide which server to route each request to.

import "sync"

// 轮训负载均衡器
type RoundRobinBalancer struct {
    lock    sync.Mutex
    servers []*websocket.Conn
    index   int
}

// 添加服务器
func (b *RoundRobinBalancer) AddServer(conn *websocket.Conn) {
    b.lock.Lock()
    defer b.lock.Unlock()
    b.servers = append(b.servers, conn)
}

// 选择服务器
func (b *RoundRobinBalancer) SelectServer() *websocket.Conn {
    b.lock.Lock()
    defer b.lock.Unlock()
    conn := b.servers[b.index]
    b.index = (b.index + 1) % len(b.servers)
    return conn
}

3. Integrate the load balancer

Now, integrate the load balancer into the WebSocket handler.

import (
    "net/http"
    "sync"

    "github.com/gorilla/websocket"
)

var (
    balancer = &RoundRobinBalancer{}
    once     sync.Once
)

// 升级 HTTP 请求并处理 WebSocket 连接
func HttpHandler(res http.ResponseWriter, req *http.Request) {
    conn, err := websocket.Upgrade(res, req, nil, 1024, 1024)
    if err != nil {
        http.Error(res, "Could not establish websocket.", http.StatusBadRequest)
        return
    }
    defer conn.Close()

    once.Do(func() {
        go balancer.Run() // 启动负载均衡器
    })

    balancer.AddServer(conn)

    // 启动协程发送数据
    go func() {
        for {
            // 读取并处理传入的消息
            _, message, err := conn.ReadMessage()
            if err != nil {
                break
            }

            conn.WriteMessage(websocket.TextMessage, []byte("消息已收到："+string(message)))
        }
    }()
}

Practical case

• Deployment server: Use Docker or Kubernetes to deploy multiple WebSocket server instances.
• Start the load balancer: Start the load balancer coroutine in the application.
• Establishing a WebSocket connection: The client can connect to any available server and the load balancer will automatically route the request to the currently available server.

By implementing these steps, you can create a highly available, scalable WebSocket application that runs efficiently even with a large number of connections.

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