How to use guzzle to simulate event loop HTTP pool - php

Question

test.php
<?php
//simulate different blocking times
if(isset($_GET['appid'])) {
sleep(rand(3, 10));
echo $_GET['appid'];
exit;
}
client.php
<?php
require './vendor/autoload.php';
use Psr\Http\Message\ResponseInterface;
use GuzzleHttp\Exception\RequestException;
use GuzzleHttp\Client;
$client = new Client();
$promise = null;
$loop = function ($appId) use($client, &$loop, &$promise) {
$promise = $client->getAsync("http://127.0.0.1/test.php?appid={$appId}");
$promise->then(
function (ResponseInterface $res) use(&$loop, $appId) {
echo $res->getBody();
//After completing the current request, initiate the request again to simulate EventLoop
$loop($appId);
},
function (RequestException $e) use(&$loop, $appId) {
//Ignore the error and continue to simulate EventLoop
$loop($appId);
}
);
};
foreach(range(1, 10) as $appId) {
$loop($appId);
}
$promise->wait();
I try to use promise to simulate EventLoop. As shown in my example code, I have 10 application IDs. I want to launch 10 requests concurrently. At the same time, the response time of each request is different. I want to launch the request of the current application ID immediately after each request is completed to simulate EventLoop.
But I find it doesn't seem to work. How can I simulate EventLoop