Using PHP curl_multi_add_handle() to Manage Multiple cURL Handles

In network request development, the PHP curl library is a widely used tool that offers many functions for performing various HTTP requests, such as GET and POST, setting headers, and handling cookies.

When sending multiple requests, creating a separate cURL handle for each request can waste resources; the curl_multi_add_handle() function allows you to add several cURL handles to one session for better management.

The syntax of curl_multi_add_handle() is:

resource curl_multi_add_handle ( resource $mh , resource $ch )

Parameters: $mh – an initialized cURL multi‑handle session. $ch – the new cURL handle to be added to the multi‑handle.

Below is a complete example that demonstrates the usage of curl_multi_add_handle():

<?php
$mh = curl_multi_init();  // initialize a multi‑handle

$ch1 = curl_init();
curl_setopt($ch1, CURLOPT_URL, "https://www.example.com/api1");
curl_setopt($ch1, CURLOPT_RETURNTRANSFER, true);
curl_multi_add_handle($mh, $ch1);  // add first handle

$ch2 = curl_init();
curl_setopt($ch2, CURLOPT_URL, "https://www.example.com/api2");
curl_setopt($ch2, CURLOPT_RETURNTRANSFER, true);
curl_multi_add_handle($mh, $ch2);  // add second handle

// Execute until all requests are finished
do {
    $status = curl_multi_exec($mh, $running);
} while ($status === CURLM_CALL_MULTI_PERFORM || $running);

// Retrieve results
$response1 = curl_multi_getcontent($ch1);
echo "Response 1: " . $response1 . "
";
$response2 = curl_multi_getcontent($ch2);
echo "Response 2: " . $response2 . "
";

// Clean up
curl_multi_remove_handle($mh, $ch1);
curl_multi_remove_handle($mh, $ch2);
curl_multi_close($mh);
?>

The example first initializes a multi‑handle with curl_multi_init(), then creates two independent cURL handles ( $ch1 and $ch2) and sets their URLs and options. Each handle is added to the multi‑handle using curl_multi_add_handle(). A loop runs curl_multi_exec() until all requests finish, after which curl_multi_getcontent() fetches each response and outputs it. Finally, the handles are removed and the multi‑handle is closed.

Using curl_multi_add_handle() efficiently manages multiple cURL sessions, improving network request performance and code maintainability. In practice, you can combine it with curl_multi_remove_handle() and curl_multi_close() for more complex request workflows.

In summary, curl_multi_add_handle() is a valuable function that lets you add several cURL handles to a single session, enabling concurrent requests, higher efficiency, and easier maintenance in real‑world development.