Monitoring policy using curl_upkeep() in connection pool

M66 2025-05-26

In PHP, cURL is a very popular library that makes HTTP requests with other servers easy and efficient. Reasonable connection pool management is particularly important when it comes to high concurrent requests. In most cases, duplicate cURL connection establishment and disconnection consumes a lot of resources and reduces the overall performance of the system. Therefore, how to manage and maintain the cURL connection pool and ensure that each connection is effectively utilized when needed without frequently creating and destroying the connection has become a key issue in development.

In this article, we will introduce how to use the curl_upkeep() function to achieve efficient connection pool management, and use this function to monitor and maintain connection activity and health, and improve overall request performance.

1. Basic concepts of connection pooling

Connection Pool is a technology used to manage multiple network connections and is often used in scenarios where frequent database operations or HTTP requests are required. Compared to establishing a new connection with each request, the connection pool can reuse existing connections between requests, reducing the overhead of connection creation.

For cURL requests, PHP provides multiple ways to manage connection pools. By properly maintaining the connection pool, it is possible to ensure that in high concurrency scenarios, connections can be reused quickly, rather than re-established every time.

2. Introduction to curl_upkeep() function

The curl_upkeep() function is not a native cURL function in PHP, but we can implement this function through custom functions. curl_upkeep() is mainly used to manage connections in connection pools, regularly check the health status of each connection, and decide whether to reconnect or continue to reuse it.

The core logic of this function is to determine whether the connection is still valid by sending requests regularly. If the connection fails, close and re-establish.

 function curl_upkeep($handle) {
    // Send a lightweight request to check if the connection is valid
    curl_setopt($handle, CURLOPT_NOBODY, true); // No need to return data
    curl_setopt($handle, CURLOPT_TIMEOUT, 10);  // Set timeout
    $response = curl_exec($handle);

    // If the connection is invalid，Close and re-establish the connection
    if ($response === false) {
        curl_close($handle);
        $handle = curl_init(); // Reinitialize cURL Handle
    }

    return $handle;
}

3. How to implement efficient connection pool management

To efficiently manage cURL connection pools, we need to regularly perform health checks on connections in the pool and clean up in time when the connection fails. By calling the curl_upkeep() function regularly, you can ensure that the connections in the pool are always in a valid state, thus avoiding request failures due to expired connections.

Here is an example showing how to use connection pools for efficient management:

 // Initialize the connection pool
$connectionPool = [];
$poolSize = 10; // Set the connection pool size

// Create a connection pool
for ($i = 0; $i < $poolSize; $i++) {
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, "https://m66.net/api"); // Use modified URL
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    $connectionPool[] = $ch;
}

// Check connections in connection pool periodically
function manage_pool($connectionPool) {
    foreach ($connectionPool as $key => $ch) {
        $connectionPool[$key] = curl_upkeep($ch);
    }
}

// Execute a request
function execute_request($connectionPool) {
    // Take a connection from the pool
    $ch = array_shift($connectionPool);

    curl_setopt($ch, CURLOPT_URL, "https://m66.net/data"); // Replace with new URL
    $response = curl_exec($ch);

    // After the request is completed，Replace the connection back into the pool
    array_push($connectionPool, $ch);

    return $response;
}

// Perform multiple requests using a connection pool
manage_pool($connectionPool);
$response = execute_request($connectionPool);
echo $response;

4. Performance optimization suggestions

Regularly maintain connection pools : Use curl_upkeep() function to regularly check the connection status in the connection pool and clean up invalid connections in time.
Reasonably configure the connection pool size : The size of the connection pool needs to be adjusted according to the system's concurrency needs. Too large pools will occupy too much resources, and too small pools will lead to frequent connection creation and destruction.
Multiplexing connections : When requesting the same domain name multiple times, make sure to reuse the existing connection instead of recreating each time.

5. Summary

By combining the curl_upkeep() function and the connection pool management strategy, PHP programs can effectively improve the performance and reliability of cURL requests. Regular health checks on the connection and timely cleaning out failed connections can ensure that the system maintains good performance in high concurrency environments. Through this method, more efficient connection management can be achieved in large-scale HTTP request scenarios, reducing connection overhead and improving response speed.

curl_upkeep