Parallel HTTP requests in PHP using PECL HTTP classes [Answer: HttpRequestPool class]

Question

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The HttpRequestPool class provides a solution. Many thanks to those who pointed this out.

A brief tutorial can be found at: http://www.phptutorial.info/?HttpRequestPool-construct

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Problem

I'd like to make concurrent/parallel/simultaneous HTTP requests in PHP. I'd like to avoid consecutive requests as:

• a set of requests will take too long to complete; the more requests the longer
• the timeout of one request midway through a set may cause later requests to not be made (if a script has an execution time limit)

I have managed to find details for making simultaneuos [sic] HTTP requests in PHP with cURL, however I'd like to explicitly use PHP's HTTP functions if at all possible.

Specifically, I need to POST data concurrently to a set of URLs. The URLs to which data are posted are beyond my control; they are user-set.

I don't mind if I need to wait for all requests to finish before the responses can be processed. If I set a timeout of 30 seconds on each request and requests are made concurrently, I know I must wait a maximum of 30 seconds (perhaps a little more) for all requests to complete.

I can find no details of how this might be achieved. However, I did recently notice a mention in the PHP manual of PHP5+ being able to handle concurrent HTTP requests - I intended to make a note of it at the time, forgot, and cannot find it again.

Single request example (works fine)

<?php
$request_1 = new HttpRequest($url_1, HTTP_METH_POST);
$request_1->setRawPostData($dataSet_1);
$request_1->send();
?>

Concurrent request example (incomplete, clearly)

<?php
$request_1 = new HttpRequest($url_1, HTTP_METH_POST);
$request_1->setRawPostData($dataSet_1);

$request_2 = new HttpRequest($url_2, HTTP_METH_POST);
$request_2->setRawPostData($dataSet_2);

// ...

$request_N = new HttpRequest($url_N, HTTP_METH_POST);
$request_N->setRawPostData($dataSet_N);

// Do something to send() all requests at the same time
?>

Any thoughts would be most appreciated!

Clarification 1: I'd like to stick to the PECL HTTP functions as:

• they offer a nice OOP interface
• they're used extensively in the application in question and sticking to what's already in use should be beneficial from a maintenance perspective
• I generally have to write fewer lines of code to make an HTTP request using the PECL HTTP functions compared to using cURL - fewer lines of code should also be beneficial from a maintenance perspective

Clarification 2: I realise PHP's HTTP functions aren't built in and perhaps I worded things wrongly there, which I shall correct. I have no concerns about people having to install extra stuff - this is not an application that is to be distributed, it's a web app with a server to itself.

Clarification 3: I'd be perfectly happy if someone authoritatively states that the PECL HTTP cannot do this.

Answer 1

I'm pretty sure HttpRequestPool is what you're looking for.

To elaborate a little, you can use forking to achieve what you're looking for, but that seems unnecessarily complex and not very useful in a HTML context. While I haven't tested, this code should be it:

// let $requests be an array of requests to send
$pool = new HttpRequestPool();
foreach ($requests as $request) {
  $pool->attach($request);
}
$pool->send();
foreach ($pool as $request) {
  // do stuff
}