Fix mysql error #2006, MySQL server has gone away for sopds_scanner

from apscheduler.schedulers.blocking import BlockingScheduler

from django.core.management.base import BaseCommand

from django.db import transaction

from django.db import transaction, connection, connections

from django.conf import settings

from opds_catalog.models import Counter

            self.restart(pid)            

    def scan(self):

        if connection.connection and not connection.is_usable():

            # destroy the default mysql connection

            # after this line, when you use ORM methods

            # django will reconnect to the default mysql

            del(connections._connections.default)

        scanner=opdsScanner(self.logger)

        with transaction.atomic():

            scanner.scan_all()