Celery: group, chain & chord: what happens on error?

Celery

Found this useful summary in Ask’s reply:

https://github.com/celery/celery/issues/1662

Group (runs in parallel): Error on one task does not stop the others

Chain (runs in serial): Error on one task halts the chain

Chord (group with callback): Error in group prevents callback from firing

Update: From Celery 3.0.14, this Chord behaviour is configurable. See CELERY_CHORD_PROPAGATES config option.