判断当前http客户端异步的任务数量

<?php
require __DIR__ . '/vendor/autoload.php';
use Workerman\Worker;
$worker = new Worker();
$worker->onWorkerStart = function(){
    $http = new Workerman\Http\Client();

    for ($i=0; $i < 10000; $i++) {
            if(/*这里我想判断正在执行的异步任务没超过256个*/) sleep(1);
            $http->get('http://example.com/', function($response){
                var_dump($response->getStatusCode());
                echo $response->getBody();
            }, function($exception){
                echo $exception;
            });
    }

};
Worker::runAll();