guzzle_pool_cancellation.php

<?php

use GuzzleHttp\Client;
use GuzzleHttp\Pool;
use GuzzleHttp\Promise\CancellationException;
use GuzzleHttp\Psr7\Request;

require 'vendor/autoload.php';

$client = new Client();

$requests = function ($total) {
    $uri = 'http://ya.ru';
    for ($i = 0; $i < $total; $i++) {
        yield new Request('GET', $uri);
    }
};

$gen = $requests(100);

$pool = new Pool($client, $gen, [
    'concurrency' => 5,
    'fulfilled' => function ($response, $index, $aggregate) {
        static $counter = 0;

        echo $response->getStatusCode() . PHP_EOL;

        $counter++;
        if ($counter >= 10) {
            echo "Stopping...\n";

            // Stop the execution and cancel all active connections
            $aggregate->cancel();
        }
    },
    'rejected' => function ($reason, $index, $aggregate) {
        var_dump($reason);
    },
]);

// Initiate the transfers and create a promise
$promise = $pool->promise();

try {
    // Force the pool of requests to complete.
    $promise->wait();
} catch (CancellationException $exception) {
    // Do nothing, because cancellation was done by the reason
}

echo "All done\n";