Lost messages in PUSH/PULL pattern ( Ratchet + PHP + ZeroMQ push integration )

Question

I'm creating a chat on my website, a push notifications system, users activity widget ( updating on the fly ) etc.

My website is built on PHP, so I decided to use Ratchet as a websocket server for my tasks. I've installed all required components and I learned the guide on http://socketo.me/docs/push and started to code.

This is inside a

ChatMsg( $item ){...}

method in the model.php
file. It creates a PUSH
socket-access-point archetype and sends a message with JSON-data to server via ZeroMQ after inserting a new item in a database:

$context = new ZMQContext();

$socket = $context->getSocket(ZMQ::SOCKET_PUSH, 'my pusher');

$socket->connect("tcp://localhost:5555");

$socket->send(json_encode($sData));

Next is my push-server.php
, creating only one PULL
socket access-point archetype and waiting for new messages, which will be transferred to the pusher script, broadcasting new notifications, chat messages and other events to clients.

<?php 

require dirname(__DIR__) . '/vendor/autoload.php';



    $loop   = React\EventLoop\Factory::create();

    $pusher = new MyApp\Pusher;



    // Listen for the web server to make a ZeroMQ push after an ajax request

    $context = new React\ZMQ\Context($loop);

    $pull = $context->getSocket(ZMQ::SOCKET_PULL);

    $pull->setSockOpt(ZMQ::SOCKOPT_HWM, 0);

    $pull->bind('tcp://127.0.0.1:5555'); // Binding to 127.0.0.1 means the only client that can connect is itself

    $pull->on('error', function ($e) {

        $f = fopen('push-server-error.log', "a");

        fwrite($f, $e->getMessage()."\n");

        fclose($f);

    });

    $pull->on('message', array($pusher, 'onNewEvent'));



    // Set up our WebSocket server for clients wanting real-time updates

    $webSock = new React\Socket\Server($loop);

    $webSock->listen(8081, '0.0.0.0'); // Binding to 0.0.0.0 means remotes can connect

    $webServer = new Ratchet\Server\IoServer(

        new Ratchet\Http\HttpServer(

            new Ratchet\WebSocket\WsServer(

                new Ratchet\Wamp\WampServer(

                    $pusher

                )

            )

        ),

        $webSock

    );



    $loop->run();

?>

I successfully started the push-server.php
with a monitoring tool Supervisor, I set up an NGINX proxying for WebSocket traffic, set up client side scripts ( autobahn and so on ).

In general, I was going to use it all at production. First hours I modified new chat systems on my website, I tested it and it all worked perfectly.

But I faced the problem a little bit later. Some ZeroMQ messages ( only part of them, maybe 5-10% ) are lost after sending via ZeroMQ

PUSH

socket. At that, this problem appears when around 300-400 messages are sent since the moment the push-server.php
process was started.

I am deeply convinced that this problem is inside the ZeroMQ ( NOT inside JS client side or Pusher script with business logic ) because I tried to modify the "->on(){...}
" method in the push-server.php
so as to display new messages on terminal ( console ) and lost messages even does not get displayed on console, i.e. the "

->on(){...}

" method does not catch up them.

ZeroMQ "->send()
" method always returns an empty ZeroMQ socket object, when a message was successfully sent or LOST. I checked this simply by sending chat messages on my website and by getting responses ( form submitting realized with AJAX ):

var_dump($socket->send(json_encode($sData)));

What there can be this problem and how to solve it?

Server OS:      CentOS 6.9 (Final)

PHP version:           5.6.31

ZMQ extension version: 1.1.3

libzmq version:        4.2.2

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Answer 1

I created not persistent ZMQ::Context and ZMQ::Socket and my problem was solved:

$context = new ZMQContext(1, false);
$socket = $context->getSocket(ZMQ::SOCKET_PUSH);

Lost messages in PUSH/PULL pattern ( Ratchet + PHP + ZeroMQ push integration )

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