How do I make an asynchronous GET request in PHP?

file_get_contents will do what you want

$output = file_get_contents('http://www.example.com/');
echo $output;

Edit: One way to fire off a GET request and return immediately.

Quoted from http://petewarden.typepad.com/searchbrowser/2008/06/how-to-post-an.html

function curl_post_async($url, $params)
{
    foreach ($params as $key => &$val) {
      if (is_array($val)) $val = implode(',', $val);
        $post_params[] = $key.'='.urlencode($val);
    }
    $post_string = implode('&', $post_params);

    $parts=parse_url($url);

    $fp = fsockopen($parts['host'],
        isset($parts['port'])?$parts['port']:80,
        $errno, $errstr, 30);

    $out = "POST ".$parts['path']." HTTP/1.1\r\n";
    $out.= "Host: ".$parts['host']."\r\n";
    $out.= "Content-Type: application/x-www-form-urlencoded\r\n";
    $out.= "Content-Length: ".strlen($post_string)."\r\n";
    $out.= "Connection: Close\r\n\r\n";
    if (isset($post_string)) $out.= $post_string;

    fwrite($fp, $out);
    fclose($fp);
}

What this does is open a socket, fire off a get request, and immediately close the socket and return.

Regarding your update, about not wanting to wait for the full page to load - I think a HTTP HEAD request is what you're looking for..

get_headers should do this - I think it only requests the headers, so will not be sent the full page content.

"PHP / Curl: HEAD Request takes a long time on some sites" describes how to do a HEAD request using PHP/Curl

If you want to trigger the request, and not hold up the script at all, there are a few ways, of varying complexities..

• Execute the HTTP request as a background process, php execute a background process - basically you would execute something like "wget -O /dev/null $carefully_escaped_url" - this will be platform specific, and you have to be really careful about escaping parameters to the command
• Executing a PHP script in the background - basically the same as the UNIX process method, but executing a PHP script rather than a shell command
• Have a "job queue", using a database (or something like beanstalkd which is likely overkill). You add a URL to the queue, and a background process or cron-job routinely checks for new jobs and performs requests on the URL

You don't. While PHP offers lots of ways to call a URL, it doesn't offer out of the box support for doing any kind of asynchronous/threaded processing per request/execution cycle. Any method of sending a request for a URL (or a SQL statement, or a etc.) is going to wait for some kind of response. You'll need some kind of secondary system running on the local machine to achieve this (google around for "php job queue")

Interesting problem. I'm guessing you just want to trigger some process or action on the other server, but don't care what the results are and want your script to continue. There is probably something in cURL that can make this happen, but you may want to consider using exec() to run another script on the server that does the call if cURL can't do it. (Typically people want the results of the script call so I'm not sure if PHP has the ability to just trigger the process.) With exec() you could run a wget or even another PHP script that makes the request with file_get_conents().

You'd better consider using Message Queues instead of advised methods. I'm sure this will be better solution, although it requires a little more job than just sending a request.

Nobody seems to mention Guzzle, which is a PHP HTTP client that makes it easy to send HTTP requests. It can work with or without Curl. It can send both synchronous and asynchronous requests.

$client = new GuzzleHttp\Client();
$promise = $client->requestAsync('GET', 'http://httpbin.org/get');
$promise->then(
    function (ResponseInterface $res) {
        echo $res->getStatusCode() . "\n";
    },
    function (RequestException $e) {
        echo $e->getMessage() . "\n";
        echo $e->getRequest()->getMethod();
    }
);

Try:

//Your Code here
$pid = pcntl_fork();
if ($pid == -1) {
     die('could not fork');
}
else if ($pid)
{
echo("Bye")  
}
else
{
     //Do Post Processing
}

This will NOT work as an apache module, you need to be using CGI.

I found this interesting link to do asynchronous processing(get request).

askapache

Furthermore you could do asynchronous processing by using a message queue like for instance beanstalkd.