How to use Swoole to implement a high-performance HTTP load balancing server

With the increasing popularity of the Internet and the popularity of mobile devices, more and more users use Internet services . This has also led to increasing pressure on Internet services, requiring the use of load balancing technology to balance the load of servers to ensure high availability and stability of services. In this article, we will introduce how to use Swoole to implement a high-performance HTTP load balancing server and provide specific code examples.

1. What is Swoole?

Swoole is an asynchronous, parallel, high-performance network communication engine based on PHP. It provides an API similar to the Node.js event firing mechanism. Swoole supports TCP/UDP/Unix Socket protocols and can be used to develop various application scenarios such as client/server, game server, Internet of Things and Web applications.

2. HTTP load balancing server architecture

Common HTTP load balancing server architecture includes four-layer load balancing and seven-layer load balancing.

Layer 4 load balancing uses IP address and port number to determine the routing of requests. Its advantage is that it is fast, but its disadvantage is that it cannot be routed based on the content of the request.

Layer 7 load balancing uses information such as URL and header to determine the routing of requests. Its advantage is that it can be routed according to the content of the request, but its disadvantage is that its performance is slightly lower.

In this article, we will use seven-layer load balancing to implement an HTTP load balancing server.

3. Implementation of HTTP load balancing server

We will use Swoole to implement HTTP load balancing server. The following are the steps to implement an HTTP load balancing server:

(1) Create a load balancer

We use Swoole's Server component to create an HTTP load balancing server, the code is as follows:

$http = new SwooleHttpServer("0.0.0.0", 9501, SWOOLE_PROCESS, SWOOLE_SOCK_TCP);

$http->on("start", function ($server) {
    echo "Swoole http server is started at http://0.0.0.0:9501
";
});

$http->on("request", function ($request, $response) {
    $response->header("Content-Type", "text/plain");
    $response->end("Hello World
");
});

$http->start();

(2) Add a backend server in the load balancer

We use Swoole's addServer method to add a backend server. After the request reaches the load balancer, the load balancer forwards the request to it according to the load balancing algorithm. Processed on a backend server. The code is as follows:

$http = new SwooleHttpServer("0.0.0.0", 9501, SWOOLE_PROCESS, SWOOLE_SOCK_TCP);

$http->on("workerStart", function ($server, $worker_id) {
    if ($worker_id == 0) {
        $server->addServer("0.0.0.0", 9502, SWOOLE_PROCESS, SWOOLE_SOCK_TCP);
        $server->addServer("0.0.0.0", 9503, SWOOLE_PROCESS, SWOOLE_SOCK_TCP);
        $server->addServer("0.0.0.0", 9504, SWOOLE_PROCESS, SWOOLE_SOCK_TCP);
    }
});

$http->on("request", function ($request, $response) {
    $response->header("Content-Type", "text/plain");
    $response->end("Hello World
");
});

$http->start();

(3) Implement the load balancing algorithm

We also need to implement the load balancing algorithm to evenly distribute requests to various back-end servers. This article uses the simplest polling algorithm to distribute requests to the back-end server in a circular manner. The code is as follows:

$http = new SwooleHttpServer("0.0.0.0", 9501, SWOOLE_PROCESS, SWOOLE_SOCK_TCP);

$servers = [
    ["host" => "127.0.0.1", "port" => 9502],
    ["host" => "127.0.0.1", "port" => 9503],
    ["host" => "127.0.0.1", "port" => 9504],
];

$current = 0;

$http->on("workerStart", function ($server, $worker_id) use ($servers, &$current) {
    if ($worker_id == 0) {
        foreach ($servers as $server) {
            $server_id = $server["host"] . ":" . $server["port"];
            $server = $server["host"];
            $port = $server["port"];
            $server = $server->addserver($server, $port, SWOOLE_PROCESS, SWOOLE_SOCK_TCP);
            $server->set(array(
                'open_length_check' => true,
                'package_max_length' => 81920,
                'package_length_type' => 'N',
                'package_body_offset' => 16,
                'package_length_offset' => 0,
            ));
            $server->on('receive', function ($server, $fd, $reactor_id, $data) use ($server_id) {
                echo "Receive data from $server_id: $data
";
                $server->send($fd, "Hello, I'm $server_id
");
            });
        }
    }
});

$http->on("request", function ($request, $response) use ($servers, &$current) {
    $server = $servers[$current];
    $host = $server["host"];
    $port = $server["port"];
    $current = ($current + 1) % count($servers);
    $client = new SwooleClient(SWOOLE_TCP);
    $client->connect($host, $port, 0.5);
    $client->send($request->rawcontent());
    $response->end($client->recv());
});

$http->start();

4. Test the HTTP load balancing server

We can use the curl command to send HTTP requests to test the performance of the HTTP load balancing server. We assume that the IP address of the HTTP load balancing server is 127.0.0.1 and the port number is 9501. We can send an HTTP request using the following command:

curl -v "http://127.0.0.1:9501/"

If everything goes well, the HTTP load balancing server should return a response similar to Hello World. When the backend server receives a request, a log similar to Receive data from 127.0.0.1:9502: GET / HTTP/1.1 will also be output. You can use these logs to verify whether the HTTP load balancing algorithm is effective.

5. Summary

In this article, we introduced how to use Swoole to implement a high-performance HTTP load balancing server and provided specific code examples. Swoole provides complete network programming and asynchronous coroutine support, which can help developers implement high-performance and high-concurrency web applications and services. I hope this article will be helpful to everyone's study and work.

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