OperationalError: (2006, 'MySQL server has gone away') after upgrading from celery 4.1.0 to 4.2.0 about django-celery-results

[oortega]

Hi, @mghantous apparently the problem comes from your task, this was my case.
By placing close_old_connections () within def store_result (........) I could see that my task in some parts took a long time and the connection with the database was lost, so also within my task place close_old_connections.

So modify store_result (): https://github.com/celery/django-celery-results/blob/master/django_celery_results/managers.py#L87

def store_result(self, content_type, content_encoding,
                 task_id, result, status,
                 traceback=None, meta=None):
    """Store the result and status of a task.
    """
    fields = {
        'status': status,
        'result': result,
        'traceback': traceback,
        'meta': meta,
        'content_encoding': content_encoding,
        'content_type': content_type,
    }
    
    #Fix temporary (2006, 'MySQL server has gone away')
    from django.db import close_old_connections
    close_old_connections()

    obj, created = self.get_or_create(task_id=task_id, defaults=fields)
    if not created:
        for k, v in items(fields):
            setattr(obj, k, v)
        obj.save()
    return obj

I hope I help you, Regards

[mghantous]

It seems to be related to this PR celery/celery#4292
When I get rid of my 'CONN_MAX_AGE': 60 setting, it seems to resolve the issue.

Perhaps I should close the issue and report it on https://github.com/celery/celery instead?

[oortega]

@mghantous same issue with:

#celery==4.0.2

amqp==2.1.4
billiard==3.5.0.2
celery==4.0.2
Django==1.11.2
django-celery-beat==1.0.1
django-celery-results==1.0.1
kombu==4.0.2
MySQL-python==1.2.5
pytz==2017.2
vine==1.1.3

After upgrade celery==4.2.1:

amqp==2.3.2
billiard==3.5.0.4
celery==4.2.1
Django==1.11.2
django-celery-beat==1.1.1
django-celery-results==1.0.1
kombu==4.2.1
MySQL-python==1.2.5
pytz==2018.5
redis==2.10.6
vine==1.1.4

[mghantous]

Thank you for the workaround. Hopefully there is a more permanent fix. The task I have been testing doesn't do anything with the database other than have its result be stored (it simply echos a message).

[auvipy]

celery/celery#4292 (comment)

[auvipy]

I hope this is fixed in celery master.