[Django]-Recover from task failed beyond max_retries

by

16👍

✅

You can override the after_return method of the celery task class, this method is called after the execution of the task whatever is the ret status (SUCCESS,FAILED,RETRY)

class MyTask(celery.task.Task)

    def run(self, xml, **kwargs)
        #Your stuffs here

    def after_return(self, status, retval, task_id, args, kwargs, einfo=None):
        if self.max_retries == int(kwargs['task_retries']):
            #If max retries are equals to task retries do something
        if status == "FAILURE":
            #You can do also something if the tasks fail instead of check the retries

http://readthedocs.org/docs/celery/en/latest/reference/celery.task.base.html#celery.task.base.BaseTask.after_return

http://celery.readthedocs.org/en/latest/reference/celery.app.task.html?highlight=after_return#celery.app.task.Task.after_return

👤Mauro Rocco

17👍

The issue is that celery is trying to re-raise the exception you passed in when it hits the retry limit. The code for doing this re-raising is here: https://github.com/celery/celery/blob/v3.1.20/celery/app/task.py#L673-L681

The simplest way around this is to just not have celery manage your exceptions at all:

@task(max_retries=10)
def mytask():
    try:
        do_the_thing()
    except Exception as e:
        try:
            mytask.retry()
        except MaxRetriesExceededError:
            do_something_to_handle_the_error()
            logger.exception(e)
👤Lucas Wiman

15👍

With Celery version 2.3.2 this approach has worked well for me:

class MyTask(celery.task.Task):
    abstract = True

    def after_return(self, status, retval, task_id, args, kwargs, einfo):
        if self.max_retries == self.request.retries:
            #If max retries is equal to task retries do something

@task(base=MyTask, default_retry_delay=5, max_retries=10)
def request(xml):
    #Your stuff here
👤Meilo

11👍

I’m just going with this for now, spares me the work of subclassing Task and is easily understood.

# auto-retry with delay as defined below. After that, hook is disabled.
@celery.shared_task(bind=True, max_retries=5, default_retry_delay=300)
def post_data(self, hook_object_id, url, event, payload):
    headers = {'Content-type': 'application/json'}
    try:
        r = requests.post(url, data=payload, headers=headers)
        r.raise_for_status()
    except requests.exceptions.RequestException as e:
        if self.request.retries >= self.max_retries:
            log.warning("Auto-deactivating webhook %s for event %s", hook_object_id, event)
            Webhook.objects.filter(object_id=hook_object_id).update(active=False)
            return False
        raise self.retry(exc=e)
    return True
👤tschottdorf

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