PHP Websocket client (ratchetphp / Pawl) + command line live output sending (popen)

Question

I need run command line app and send live output to websocket server:

<?php
$loop = React\EventLoop\Factory::create();
$connector = new Ratchet\Client\Connector($loop);

$app = function (Ratchet\Client\WebSocket $conn) use ($connector, $loop, &$app, $server_id) {
    $conn->on('message', function (\Ratchet\RFC6455\Messaging\MessageInterface $msg) use ($conn) {
        global $server_id;
        $msg = json_decode($msg);
        if($msg->type=='run') {
            $proc = popen("ping -t 127.0.0.1",'r');
            while (!feof($proc))
            {
                $read = fread($proc, 4096);
                if($read) {
                    $conn->send($read);
                }
            }
        }
    });

    $conn->on('close', function ($code = null, $reason = null) use ($connector, $loop, $app) {
        echo "Connection closed ({$code} - {$reason})\n";
        $loop->addTimer(3, function () use ($connector, $loop, $app) {
            connectToServer($connector, $loop, $app);
        });
    });
};
function connectToServer($connector, $loop, $app)
{
    $connector('wss://server:1234')
        ->then($app, function (\Exception $e) use ($loop) {
            echo "Could not connect: {$e->getMessage()}\n";
            $loop->stop();
        });
}

connectToServer($connector, $loop, $app);
$loop->run();

The problem is when i try to use while (!feof($proc)) it looks like blocks main thread and $conn->send($read); doesn't send anything inside while... Any way to use popen and Pawl?