Symfony4: Gos Websocket Error: MySQL server has gone away - symfony

Question

I have enabled the PDO Periodic Pings for GOS:WebSocketBundle, I'm still getting this error from time to time:
09:41:28 ERROR [websocket] Connection error occurred Warning: Error
while sending QUERY packet. PID=30536 in /home/dev.symfony/libs/composer_vendor/doctrine/dbal/lib/Doctrine/DBAL/Driver/PDOStatement.php
10:00:23 ERROR [websocket] Connection error occurred
SQLSTATE[HY000]: General error: 2006 MySQL server has gone away in
/home/dev.symfony/libs/composer_vendor/doctrine/dbal/lib/Doctrine/DBAL/Driver/PDOStatement.php
line 107 ["connection_id" => 3365,"session_id" =>
"11667050395acf121709d30728596936"] []
Another point is that if nobody use dev server, in logs no errors, but if I login to this immediatelly appear this error.
There is issue opened also on github https://github.com/GeniusesOfSymfony/WebSocketBundle/issues/299
but no answers, so I asked also here. Thank you.

Answer 1

Solved. Problem was that I defined periodic timer inside Topic inside "onSubscribe" funciton like:
public function onSubscribe(ConnectionInterface $connection, Topic $topic, WampRequest $request)
{
...
$topicTimer = $connection->PeriodicTimer;
//Add periodic timer every 3 seconds update
$topicTimer->addPeriodicTimer('notifications', 3, function() use ($topic, $connection) {
$user = $this->clientManipulator->getClient($connection);
if($user) {
$counters = $this->globalVariables->getCounters($user);
$connection->event($topic->getId(),['msg' => $counters]);
}
});
...
}
But now I switched to "standalone" periodic like it described here https://github.com/GeniusesOfSymfony/WebSocketBundle/blob/master/Periodic/PdoPeriodicPing.php
and attached this to websocket. Now there is no timeout with database.

Answer 2

It's worth noting that when you follow the Symfony documentation with creating PdoSessionHandler http://symfony.com/doc/current/doctrine/pdo_session_storage.html where you are passing the dsn instead of pdo service it won't work, because the session handler will create other connection. To solve this create a pdo service and pass it to the PdoSessionHandler like it is described in the https://github.com/GeniusesOfSymfony/WebSocketBundle/blob/master/Resources/docs/SessionSetup.md