Load balancing implementation method in Workerman documentation

Workerman is a high-performance network framework developed based on PHP, which is widely used to build real-time communication systems and high-concurrency services. In actual application scenarios, we often need to improve system reliability and performance through load balancing. This article will introduce how to implement load balancing in Workerman and provide specific code examples.

Load balancing refers to allocating network traffic to multiple back-end servers to achieve the purpose of improving the system's load capacity, reducing response time, and increasing system availability and scalability. In Workerman, we can achieve load balancing in a variety of ways. Two common methods will be introduced below: polling-based load balancing and weight-based load balancing.

1. Poll-based load balancing
   Poll-based load balancing is the simplest load balancing algorithm, which distributes each request to the backend server in turn. In Workerman, we can save the backend server list by using an array, and use a variable to record the currently allocated backend server location. The specific code example is as follows:

$backends = array(
    '127.0.0.1:8081',
    '127.0.0.1:8082',
    '127.0.0.1:8083'
);
$backendIndex = 0;

$worker = new Worker('tcp://0.0.0.0:8080');

$worker->onConnect = function($connection) use ($backends, &$backendIndex) {
    $remoteAddress = $backends[$backendIndex];
    $backendIndex = ($backendIndex + 1) % count($backends);
    $backendConnection = new AsyncTcpConnection('tcp://' . $remoteAddress);
    $backendConnection->onConnect = function($backendConnection) use ($connection) {
        // 连接后端服务器成功，将后端服务器连接的数据回传给客户端连接
        $backendConnection->pipe($connection);
        $connection->pipe($backendConnection);
    };
    $connection->backendConnection = $backendConnection;
    $backendConnection->connect();
};

$worker->onMessage = function($connection, $data) {
    // 将客户端发送的数据传递给后端服务器
    $connection->backendConnection->send($data);
};

In the above code, the $backends array stores the IP address and port number of the backend server, and the variable $backendIndex is used to record the location of the currently allocated backend server. . When a new connection is established on the client, the request is allocated to the back-end server in a polling manner, and after the connection is successfully established, the back-end server connection data is passed back to the client connection. When the client sends data, pass the data to the backend server.

2. Weight-based load balancing
   The weight-based load balancing algorithm allocates requests based on the weight value of the backend server. In Workerman, we can save the list of backend servers by using an array containing weights and select the backend server through a random number generator. The specific code example is as follows:

$backends = array(
    array('address' => '127.0.0.1:8081', 'weight' => 1),
    array('address' => '127.0.0.1:8082', 'weight' => 2),
    array('address' => '127.0.0.1:8083', 'weight' => 3)
);

$worker = new Worker('tcp://0.0.0.0:8080');

$worker->onConnect = function($connection) use ($backends) {
    $totalWeight = array_sum(array_column($backends, 'weight'));
    $random = rand(1, $totalWeight);
    foreach ($backends as $backend) {
        $random -= $backend['weight'];
        if ($random <= 0) {
            $remoteAddress = $backend['address'];
            break;
        }
    }
    $backendConnection = new AsyncTcpConnection('tcp://' . $remoteAddress);
    $backendConnection->onConnect = function($backendConnection) use ($connection) {
        // 连接后端服务器成功，将后端服务器连接的数据回传给客户端连接
        $backendConnection->pipe($connection);
        $connection->pipe($backendConnection);
    };
    $connection->backendConnection = $backendConnection;
    $backendConnection->connect();
};

$worker->onMessage = function($connection, $data) {
    // 将客户端发送的数据传递给后端服务器
    $connection->backendConnection->send($data);
};

In the above code, the $backends array stores the IP address and port number of the backend server and the corresponding weight value. When a new connection is established on the client, the back-end server is selected based on the weight value of the back-end server, and after the connection is successfully established, the back-end server connection data is sent back to the client connection. When the client sends data, pass the data to the backend server.

Through the above two load balancing implementation methods, we can easily build highly available and high-performance network applications in Workerman. In practical applications, we can choose a suitable load balancing algorithm according to needs and flexibly apply it according to actual scenarios.

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