Функция получатель
from .management.commands.db_hour import Command, usr_hour
from django.dispatch import receiver
from .models import MySession, Session, Board

usr_in_hour = []

@receiver(usr_hour, sender=Command)
def my_callback(sender, **kwargs):
    usr_in_hour.clear()
    boards = Board.objects.all().values('board_shortcut')
    for x in boards:
        usr_in_hour.append(MySession.objects.filter(name_board__contains=x['board_shortcut']).count())

Своя команда и функция отправитель
from django.core.management.base import BaseCommand
from django.utils import timezone
import datetime
from boards.models import MySession, Session
from django.dispatch import Signal

usr_hour = Signal(providing_args=[])

class Command(BaseCommand):

    def handle(self, *args, **options):
        now = timezone.now()
        two_hour = now - datetime.timedelta(hours=2)
        MySession.objects.filter(expire_date__range=(two_hour, now)).delete()
        Session.objects.filter(expire_date__range=(two_hour, now)).delete()

        usr_hour.send(sender=self.__class__)

        self.stdout.write('Succes')
Вьюха
from .signals import usr_in_hour

# Create your views here.

def index(request):
    boards = Board.objects.all()
    for board in boards:
        board.board_posts = Thread.objects.filter(board=board).count() + Comment.objects.filter(thread__board=board).count()
    return render(request ,'index.html', {'boards': boards, 'usr_in_hour': usr_in_hour})