Files needed to reproduce Celery issue

flow.py

from __future__ import print_function

import pprint
import time

from celery import group, chain, chord

import simple_tasks as t

workflow = chain(
    t.task1.s(),
    chord(
        [
            t.task2.s(),
            chain(
                t.task3.s(),
                chord(
                    [t.task4.s(), t.task5.s()],
                    t.task6.s()
                )
            )
        ],
        t.task7.s()
    )
)

#workflow = chain(
#    t.task1.s(),
#    group(
#        t.task2.s(),
#        chain(
#            t.task3.s(),
#            group(t.task4.s(), t.task5.s())
#        )
#    )
#)

result = workflow.delay()

def print_status(result):
    print("{} ".format(result.__class__.__name__), end='')

    if hasattr(result, 'state'):
        print("{} {} ({})".format(result.task_name, result.id, result.state))
    else:
        print("{}".format(result.id))

    if result.parent:
        print_status(result.parent)

    if result.children:
        for r in result.children:
            print_status(r)

while not result.ready():
    print_status(result)
    time.sleep(5)
else:
    print_status(result)

running-flow.log

$ python flow.py
AsyncResult None 957b64a0-b219-4e91-9bb9-cf43d2ee3a6e (PENDING)
AsyncResult None c772cd4f-775b-4340-9ff9-e306ee84f4e4 (PENDING)
AsyncResult None 957b64a0-b219-4e91-9bb9-cf43d2ee3a6e (PENDING)
AsyncResult None c772cd4f-775b-4340-9ff9-e306ee84f4e4 (STARTED)
AsyncResult None 957b64a0-b219-4e91-9bb9-cf43d2ee3a6e (PENDING)
AsyncResult None c772cd4f-775b-4340-9ff9-e306ee84f4e4 (SUCCESS)
GroupResult 7d427845-8725-49dd-9af6-cca32d35b0e5
AsyncResult None b4603400-cd2b-4a00-bd91-06f21cc04ebc (STARTED)
AsyncResult None 3eadb949-3b36-407d-8a61-b7498c4eece9 (PENDING)
AsyncResult None 957b64a0-b219-4e91-9bb9-cf43d2ee3a6e (PENDING)
AsyncResult None c772cd4f-775b-4340-9ff9-e306ee84f4e4 (SUCCESS)
GroupResult 7d427845-8725-49dd-9af6-cca32d35b0e5
AsyncResult None b4603400-cd2b-4a00-bd91-06f21cc04ebc (SUCCESS)
AsyncResult None 3eadb949-3b36-407d-8a61-b7498c4eece9 (PENDING)
AsyncResult None 957b64a0-b219-4e91-9bb9-cf43d2ee3a6e (PENDING)
AsyncResult None c772cd4f-775b-4340-9ff9-e306ee84f4e4 (SUCCESS)
GroupResult 7d427845-8725-49dd-9af6-cca32d35b0e5
AsyncResult None b4603400-cd2b-4a00-bd91-06f21cc04ebc (SUCCESS)
AsyncResult None 3eadb949-3b36-407d-8a61-b7498c4eece9 (PENDING)
AsyncResult None 957b64a0-b219-4e91-9bb9-cf43d2ee3a6e (PENDING)
AsyncResult None c772cd4f-775b-4340-9ff9-e306ee84f4e4 (SUCCESS)
GroupResult 7d427845-8725-49dd-9af6-cca32d35b0e5
AsyncResult None 957b64a0-b219-4e91-9bb9-cf43d2ee3a6e (PENDING)
AsyncResult None c772cd4f-775b-4340-9ff9-e306ee84f4e4 (SUCCESS)
...

running-workers.log

$ celery worker -A simple_tasks -l info

 -------------- [email protected] v3.1.17 (Cipater)
---- **** -----
--- * ***  * -- Darwin-14.1.0-x86_64-i386-64bit
-- * - **** ---
- ** ---------- [config]
- ** ---------- .> app:         simple_tasks:0x1010ec1d0
- ** ---------- .> transport:   redis://localhost:6379/0
- ** ---------- .> results:     redis://localhost:6379/0
- *** --- * --- .> concurrency: 8 (prefork)
-- ******* ----
--- ***** ----- [queues]
 -------------- .> celery           exchange=celery(direct) key=celery


[tasks]
  . simple_tasks.task1
  . simple_tasks.task2
  . simple_tasks.task3
  . simple_tasks.task4
  . simple_tasks.task5
  . simple_tasks.task6
  . simple_tasks.task7

Connected to redis://localhost:6379/0
mingle: searching for neighbors
mingle: all alone
[email protected] ready.
Received task: simple_tasks.task1[c772cd4f-775b-4340-9ff9-e306ee84f4e4]
task1 start
task1 finish
Received task: simple_tasks.task2[b4603400-cd2b-4a00-bd91-06f21cc04ebc]
Received task: simple_tasks.task3[a1805e5f-302c-4e56-9c19-080036dd347b]
Task simple_tasks.task1[c772cd4f-775b-4340-9ff9-e306ee84f4e4] succeeded in 5.02584462601s: 'result task1'
task2 start
task3 start
task2 finish
task3 finish
Task simple_tasks.task2[b4603400-cd2b-4a00-bd91-06f21cc04ebc] succeeded in 5.00715394001s: 'result task2'
Received task: simple_tasks.task4[8f6c8ad3-b5b3-40c2-bc97-5f9e6a71a4bc]
Task simple_tasks.task3[a1805e5f-302c-4e56-9c19-080036dd347b] succeeded in 5.024643707s: 'result task3'
Received task: simple_tasks.task5[23222361-0d3c-4d5b-b40f-60d17449e343]
task4 start
task5 start
task4 finish
task5 finish
Task simple_tasks.task4[8f6c8ad3-b5b3-40c2-bc97-5f9e6a71a4bc] succeeded in 5.00776234898s: 'result task4'
Received task: simple_tasks.task6[58a3ebcf-6bb1-43dd-8e21-dd3f2a3d6d9f]
Task simple_tasks.task5[23222361-0d3c-4d5b-b40f-60d17449e343] succeeded in 5.528548242s: 'result task5'
task6 start
task6 finish
Task simple_tasks.task6[58a3ebcf-6bb1-43dd-8e21-dd3f2a3d6d9f] succeeded in 5.005484494s: 'result task6'

simple_tasks.py

from __future__ import print_function
import time

from celery import Celery

redis_uri = "redis://%(host)s:%(port)d/%(db)d" % dict(
    host = 'localhost',
    port = 6379,
    db = 0
)

app = Celery(__name__)

app.conf.update(
    BROKER_URL = redis_uri,
    CELERY_RESULT_BACKEND = redis_uri,
    CELERY_TASK_SERIALIZER = 'pickle',
    CELERY_RESULT_SERIALIZER = 'pickle',
    CELERY_ACCEPT_CONTENT = ['pickle'],
    CELERYD_LOG_FORMAT = "%(message)s",
    CELERY_TRACK_STARTED = True,
)

def run_task(num):
    print("task%d start" % num)
    time.sleep(5)
    print("task%d finish" % num)
    return "result task%d" % num

@app.task
def task1(*args, **kwargs):
    return run_task(1)

@app.task
def task2(*args, **kwargs):
    return run_task(2)

@app.task
def task3(*args, **kwargs):
    return run_task(3)

@app.task
def task4(*args, **kwargs):
    return run_task(4)

@app.task
def task5(*args, **kwargs):
    return run_task(5)

@app.task
def task6(*args, **kwargs):
    return run_task(6)

@app.task
def task7(*args, **kwargs):
    return run_task(7)

if __name__ == '__main__':
    app.worker_main()