test.py

# -*- coding: utf-8 -*-

from celery import Celery, group, chain, chord

app = Celery('tasks', broker='redis://localhost:6379/0', backend='redis://localhost:6379/0?new_join=1')
app.conf.CELERY_CHORD_PROPAGATE = True
@app.task
def add(x):
    if(x == 3):
        raise Exception('arg')
    print x

@app.task()
def tend():
    print "this is the end"

lst = [add.si(1),add.si(2), add.si(3)]
chord(lst)(tend.si())


# 
# [2015-10-07 16:50:23,062: WARNING/Worker-4] 1
# [2015-10-07 16:50:23,064: INFO/MainProcess] Received task: test.add[e37117be-d087-4324-855d-5d409b3c3e85]
# [2015-10-07 16:50:23,064: WARNING/Worker-5] 2
# [2015-10-07 16:50:23,066: INFO/MainProcess] Task test.add[e4370b23-fe1c-4c91-a5f8-9ad7c0b5f06d] succeeded in 0.00449428195134s: None
# [2015-10-07 16:50:23,067: INFO/MainProcess] Task test.add[ab6330f0-da73-4bdf-bcd1-fb34aec09453] succeeded in 0.00339785998221s: None
# [2015-10-07 16:50:23,070: ERROR/Worker-1] Chord callback for '4676180e-9481-425c-aa56-8f008bf2eae5' raised: ChordError("Dependency e37117be-d087-4324-855d-5d409b3c3e85 raised <ExceptionInfo: Exception('arg',)>",)
# Traceback (most recent call last):
#   File "venv/lib/python2.7/site-packages/celery/backends/redis.py", line 224, in _new_chord_return
#     callback.delay([unpack(tup, decode) for tup in resl])
#   File "venv/lib/python2.7/site-packages/celery/backends/redis.py", line 187, in _unpack_chord_result
#     raise ChordError('Dependency {0} raised {1!r}'.format(tid, retval))
# ChordError: Dependency e37117be-d087-4324-855d-5d409b3c3e85 raised <ExceptionInfo: Exception('arg',)>
# [2015-10-07 16:50:23,073: ERROR/MainProcess] Task test.add[e37117be-d087-4324-855d-5d409b3c3e85] raised unexpected: Exception('arg',)
# Traceback (most recent call last):
#   File "venv/lib/python2.7/site-packages/celery/app/trace.py", line 240, in trace_task
#     R = retval = fun(*args, **kwargs)
#   File "venv/lib/python2.7/site-packages/celery/app/trace.py", line 438, in __protected_call__
#     return self.run(*args, **kwargs)
#   File "test.py", line 10, in add
#     raise Exception('arg')
# Exception: arg