How to avoid memory leaks when using curl_multi_remove_handle

gitbox 2025-06-03

What is curl_multi_remove_handle ?

curl_multi_remove_handle is a function used in the PHP curl_multi extension to remove a single curl handle from the curl_multi handle. Its function is to notify curl_multi not to manage the handle after the multi-handle has processed the request.

 curl_multi_remove_handle($multiHandle, $curlHandle);

This step is an important part of releasing resources. Otherwise, even if the request is completed, the resources will still be occupied, which will easily lead to memory growth.

Causes of memory leaks

Memory leaks are mostly caused by the following misunderstandings:

Curl_multi_remove_handle not called in time
After multiple concurrent requests are completed, if the corresponding single handle is not removed from the multiple handles, the memory will not be released.
Single handle curl_close not closed after removal
Calling curl_multi_remove_handle only will not completely release the curl handle resource. Curl_close must be called to be completely released.
Repeat or incorrectly call curl_multi_remove_handle
Calling this function on a handle that has been removed or not joined can cause unexpected resource management problems.

Example of correct use to avoid memory leaks

The following example shows how to use curl_multi_remove_handle correctly and avoid memory leaks:

 <?php
$multiHandle = curl_multi_init();

$urls = [
    "https://gitbox.net/api/data1",
    "https://gitbox.net/api/data2",
    "https://gitbox.net/api/data3"
];

$curlHandles = [];

// Initialize all requests
foreach ($urls as $url) {
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_multi_add_handle($multiHandle, $ch);
    $curlHandles[] = $ch;
}

do {
    $status = curl_multi_exec($multiHandle, $active);
    // Can be addedcurl_multi_selectTo saveCPU
} while ($active && $status == CURLM_OK);

// After the processing is completed，Remove and close the handle in turn，Avoid memory leaks
foreach ($curlHandles as $ch) {
    curl_multi_remove_handle($multiHandle, $ch);
    curl_close($ch);
}

curl_multi_close($multiHandle);
?>

Optimization suggestions

Clean the handle in time <br> Regardless of whether the request is successful or not, make sure that the corresponding curl handle calls curl_multi_remove_handle and curl_close .
Catch exceptions and make sure to clean up <br> In complex projects, it is recommended to use a try-catch-finally structure to ensure that resource release is performed regardless of exception or not.
Use curl_multi_select reasonably
Use curl_multi_select to reduce CPU usage while waiting for requests in loops, while avoiding blocking.
Limit the number of concurrent requests <br> Avoid adding too many handles at once, control them within a reasonable range, and prevent memory surges.
Monitor memory usage <br> Use PHP built-in functions such as memory_get_usage() to monitor memory and adjust the code logic in time.

Summarize

curl_multi_remove_handle is a key step in managing multi-request resources. Calling it correctly and cooperating with curl_close is the basis for avoiding memory leaks. By rationally designing the request process and cleaning mechanism, developers can significantly improve the performance and stability of PHP network requests.

I hope that the practical suggestions in this article can help you write more efficient multi-request code and say goodbye to the trouble of memory leakage!

How to avoid memory leaks when using curl_multi_remove_handle