Mastering curl_multi_close(): Properly Release Multi‑cURL Resources in PHP

When making network requests in PHP, the cURL library is commonly used, and the curl_multi_close() function is used to close multiple cURL sessions.

The curl_multi_close() function releases resources allocated by curl_multi_init() after all requests have been processed, which is a good practice.

Example

<?php
// Create multiple cURL sessions
$multiHandle = curl_multi_init();

// Add first request
$ch1 = curl_init();
curl_setopt($ch1, CURLOPT_URL, 'https://example.com/api/1');
curl_setopt($ch1, CURLOPT_RETURNTRANSFER, true);
curl_multi_add_handle($multiHandle, $ch1);

// Add second request
$ch2 = curl_init();
curl_setopt($ch2, CURLOPT_URL, 'https://example.com/api/2');
curl_setopt($ch2, CURLOPT_RETURNTRANSFER, true);
curl_multi_add_handle($multiHandle, $ch2);

// Execute and wait for all requests to complete
// ...

// Close sessions
curl_multi_close($multiHandle);
?>

The example first creates a multi‑handle with curl_multi_init(), then initializes two individual handles with curl_init(), sets URLs and options, adds them to the multi‑handle via curl_multi_add_handle(), and finally closes the multi‑handle with curl_multi_close() to free resources.

Summary

The curl_multi_close() function is essential for properly releasing resources created by curl_multi_init(), ensuring better performance and avoiding leaks when handling concurrent network requests in PHP.