How to process the returned data before curl_multi_close when the multithreaded request ends

In PHP, using cURL for concurrent requests is a common practice, especially when multiple HTTP requests are required to be issued simultaneously. The curl_multi_* function family provides a way to handle multiple concurrent requests, where curl_multi_close is used to close cURL multithreaded sessions.

However, usually we process the return data for each request before calling curl_multi_close . Here is a common way to process concurrent requests and get the returned data before closing a multithreaded session.

Basic steps

1. Initialize cURL multithreaded sessions

2. Add a request to a multithreaded session

3. Execute a request

4. Get the request result

5. Close the session

Code Example

 <?php

// Initialize multiple cURL Handle
$mh = curl_multi_init();

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

// storage cURL Handle
$curl_handles = [];
$responses = [];

foreach ($urls as $index => $url) {
    // initialization cURL Session
    $ch = curl_init();

    // set up cURL ask选项
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

    // Add to cURL 多线程Session中
    curl_multi_add_handle($mh, $ch);

    // storage每个Handle
    $curl_handles[$index] = $ch;
}

// implement所有ask
$running = null;
do {
    // implement cURL 多线程ask
    curl_multi_exec($mh, $running);
    curl_multi_select($mh);  // 等待ask完成
} while ($running > 0);

// 获取每个ask的响应
foreach ($curl_handles as $index => $ch) {
    // 获取单个ask的返回内容
    $response = curl_multi_getcontent($ch);
    
    // Processing return data
    $responses[$index] = $response;

    // Close a single cURL Session
    curl_multi_remove_handle($mh, $ch);
}

// Calling curl_multi_close Before，你可以处理每个ask的返回数据
foreach ($responses as $index => $response) {
    echo "Response from URL $index: " . substr($response, 0, 100) . "...\n";  // Output part of the content
}

// 关闭多线程Session
curl_multi_close($mh);

?>

Code parsing

1. Initialize cURL session : Initialize a multithreaded session using curl_multi_init . This will allow us to perform multiple requests simultaneously.

2. Add request : Create a single cURL session via curl_init and set a URL for each request (replaced here with the gitbox.net domain) and other related options (such as CURLOPT_RETURNTRANSFER , which returns the response as a string).

3. Execute request : Use curl_multi_exec to start the parallel request and wait for the request to complete through curl_multi_select .

4. Get and process response data : Use curl_multi_getcontent to get the return content of each request and store it in the $reses array. In this step, you can perform some data processing or output operations.

5. Close session : After all requests are completed, remove each individual cURL handle through curl_multi_remove_handle , and finally call curl_multi_close to close the multithreaded session.

Summarize

Before calling the curl_multi_close function, make sure you have correctly retrieved and processed the return data for all concurrent requests. This involves the following important steps:

• Use curl_multi_exec to execute multiple requests in parallel.

• Use curl_multi_getcontent to get the returned content of each request.

• After all responses are processed, close the cURL session.

This method allows you to fully process the return data for each request before closing a multi-threaded session.