signals.py

from celery.registry import tasks
from celery.signals import task_sent, task_prerun, task_postrun

def on_task_postrun(**kwargs):
    print "on_task_postrun"

def on_task_sent(**kwargs):
    print "on_task_sent"

task_sent.connect(on_task_sent, tasks['documents.tasks.CreateBoardbook'])
task_postrun.connect(on_task_postrun, tasks['documents.tasks.CreateBoardbook'])

subtask.py

from celery.task import task
from celery.task.sets import subtask

from accounts.models import BRUser
from meetings.models import Meeting
from documents.tasks import CreateBoardbook

s = subtask("hello", args=(), kwargs={})
@task
def hello():
    print "Hello"

boardbook_task = CreateBoardbook()
user = BRUser.objects.get(email='bench-test-member0001@sherpany.com')
meeting = Meeting.objects.get(id=14)
boardbook_task.delay(meeting, user, True, True)
boardbook_task.subtask(dict(s))

works.py

from celery.signals import task_sent, task_prerun, task_postrun

@task_sent.connect
def task_sent_handler(sender="documents.tasks.CreateBoardbook", **kwds):
    print "Got signal task_sent"

# Not working
@task_postrun.connect
def task_postrun_handler(sender="documents.tasks.CreateBoardbook", **kwds):
    print "Got signal task_postrun"