How to use curl_upkeep() to reduce the pressure on the server

In modern web applications, frequent HTTP requests and response interactions with servers are very common requirements. Every time you establish a connection, send a request and close the connection, it consumes a lot of resources and time, especially when facing high concurrent requests, which may put a lot of pressure on the server. To optimize performance and reduce server load, we can use a method called keeping connections active, where the curl function in PHP can help us achieve this.

In this article, we will focus on how to keep HTTP connections active through the curl_upkeep() function, thereby reducing the performance problems caused by frequent rebuilding of connections.

Why do you need to keep your connection active?

Every time an HTTP request is initiated to the server through curl , it will go through the process of establishing a connection, sending data, receiving data, and closing the connection. For each request, establishing and disconnecting consumes system resources. Especially in the case of high concurrency, frequent establishment and closing of connections can lead to server overload.

By using the Keep-Alive feature, you can avoid re-establishing the connection every time you request. HTTP Keep-Alive allows connections to remain open after sending requests, allowing multiple requests to share a connection, reducing the number of TCP connections established and demolished, thereby reducing server pressure and improving performance.

Use curl_upkeep() to keep the connection active

In PHP, curl is a very powerful tool for sending HTTP requests and processing server responses. To keep the connection active, we can set some options in the curl configuration.

Suppose we already have a basic curl request, and now we want to modify it so that it can keep the connection active:

 <?php
function curl_upkeep($url) {
    // initialization cURL Session
    $ch = curl_init();

    // Setting target URL
    curl_setopt($ch, CURLOPT_URL, $url);

    // Set the request method to GET
    curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "GET");

    // Enable return value instead of output
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

    // Set header information，Supports keeping connected
    curl_setopt($ch, CURLOPT_HTTPHEADER, [
        "Connection: keep-alive"
    ]);

    // Set the maximum number of retry times and retry interval
    curl_setopt($ch, CURLOPT_MAXREDIRS, 3);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);

    // Execute a request and get a response
    $response = curl_exec($ch);

    // Check if an error has occurred
    if(curl_errno($ch)) {
        echo "cURL error: " . curl_error($ch);
    }

    // closure cURL Session
    curl_close($ch);

    // Return response
    return $response;
}

// use m66.net As an example URL
$response = curl_upkeep("https://m66.net/api/getData");
echo $response;
?>

Key points analysis

1. Stay connected :

   • We add a Connection: keep-alive HTTP header by setting the CURLOPT_HTTPHEADER option in curl_setopt() . This header tells the server that the client wants to keep the current connection active after sending the response and can accept subsequent requests.

2. Maximum redirects :

   • The CURLOPT_MAXREDIRS option controls the maximum number of redirects allowed. In some cases, the server may return a redirect response (such as 301 or 302), and we can limit the number of redirects through this option to prevent infinite loops.

3. Follow Redirect :

   • CURLOPT_FOLLOWLOCATION is set to true to allow cURL to follow the 3xx class redirect response. This is very important to ensure that the request can reach the final location of the target server.

4. Error handling :

   • We use curl_errno() and curl_error() to capture and output possible errors to ensure that errors can be diagnosed in time.

5. Response returns :

   • curl_exec() will return the server's response data, which we store and return for subsequent processing.

Summarize

By using the keep connection option in curl , we can significantly reduce the server pressure from frequent connection creation and closing. Especially when handling a large number of requests, keeping the connection active can effectively improve application performance, reduce latency, and optimize user experience. We enhance the reliability and flexibility of requests by setting Connection: keep-alive to make the connection lasting and setting other curl options.

Hopefully, through this article, you can better understand how to use curl_upkeep() to keep connection active and reduce the pressure on the server due to frequent rebuilding of connections.