public function find($entityName, $id, $lockMode = null, $lockVersion = null)
    {
        try{
            return $this->entityManager->find($entityName, $id, $lockMode, $lockVersion);
        } catch(ORMException $e) {
            if (!$this->entityManager->isOpen()) {
                $this->resetEntityManager();
            }
            throw $e;
        }
    }