What is the meaning of bind=True in below celery code? When to use it and when not?
@app.task(bind=True)
def send_twitter_status(self, oauth, tweet):
try:
twitter = Twitter(oauth)
twitter.update_status(tweet)
except (Twitter.FailWhaleError, Twitter.LoginError) as exc:
raise self.retry(exc=exc)
Bound tasks
A task being bound means the first argument to the task will always be the task instance (self), just like Python bound methods:
logger = get_task_logger(__name__)
@task(bind=True)
def add(self, x, y):
logger.info(self.request.id)
Just a small addition to other answers. As already stated, bound tasks have access to the task instance. One use case when this is needed are retries:
@celery.task(bind=True, max_retries=5)
def retrying(self):
try:
return 1/0
except Exception:
self.retry(countdown=5)
Another use case is when you want to define custom states for your tasks and be able to set it during task execution:
@celery.task(bind=True)
def show_progress(self, n):
for i in range(n):
self.update_state(state='PROGRESS', meta={'current': i, 'total': n})