gunicorn 19.x causing problems with django-1.7.1 and gevent

[daltonmatos]

Hello,

I'm seeing this error with gunicorn 19.x (tested with 19.0 and 19.1.1) using the gevent worker. I'm using django-1.7.1.

this is the exception:

Traceback:
File "/home/sieve/sitroom.sieve.com.br/shared/env/local/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
  87.                 response = middleware_method(request)
File "/home/sieve/sitroom.sieve.com.br/shared/env/local/lib/python2.7/site-packages/django/contrib/auth/middleware.py" in process_request
  34.         if user and hasattr(user, 'get_session_auth_hash'):
File "/home/sieve/sitroom.sieve.com.br/shared/env/local/lib/python2.7/site-packages/django/utils/functional.py" in inner
  224.             self._setup()
File "/home/sieve/sitroom.sieve.com.br/shared/env/local/lib/python2.7/site-packages/django/utils/functional.py" in _setup
  357.         self._wrapped = self._setupfunc()
File "/home/sieve/sitroom.sieve.com.br/shared/env/local/lib/python2.7/site-packages/django/contrib/auth/middleware.py" in <lambda>
  23.         request.user = SimpleLazyObject(lambda: get_user(request))
File "/home/sieve/sitroom.sieve.com.br/shared/env/local/lib/python2.7/site-packages/django/contrib/auth/middleware.py" in get_user
  11.         request._cached_user = auth.get_user(request)
File "/home/sieve/sitroom.sieve.com.br/shared/env/local/lib/python2.7/site-packages/django/contrib/auth/__init__.py" in get_user
  151.         user_id = request.session[SESSION_KEY]
File "/home/sieve/sitroom.sieve.com.br/shared/env/local/lib/python2.7/site-packages/django/contrib/sessions/backends/base.py" in __getitem__
  49.         return self._session[key]
File "/home/sieve/sitroom.sieve.com.br/shared/env/local/lib/python2.7/site-packages/django/contrib/sessions/backends/base.py" in _get_session
  175.                 self._session_cache = self.load()
File "/home/sieve/sitroom.sieve.com.br/shared/env/local/lib/python2.7/site-packages/django/contrib/sessions/backends/db.py" in load
  21.                 expire_date__gt=timezone.now()
File "/home/sieve/sitroom.sieve.com.br/shared/env/local/lib/python2.7/site-packages/django/db/models/manager.py" in manager_method
  92.                 return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/home/sieve/sitroom.sieve.com.br/shared/env/local/lib/python2.7/site-packages/django/db/models/query.py" in get
  351.         num = len(clone)
File "/home/sieve/sitroom.sieve.com.br/shared/env/local/lib/python2.7/site-packages/django/db/models/query.py" in __len__
  122.         self._fetch_all()
File "/home/sieve/sitroom.sieve.com.br/shared/env/local/lib/python2.7/site-packages/django/db/models/query.py" in _fetch_all
  966.             self._result_cache = list(self.iterator())
File "/home/sieve/sitroom.sieve.com.br/shared/env/local/lib/python2.7/site-packages/django/db/models/query.py" in iterator
  265.         for row in compiler.results_iter():
File "/home/sieve/sitroom.sieve.com.br/shared/env/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py" in results_iter
  700.         for rows in self.execute_sql(MULTI):
File "/home/sieve/sitroom.sieve.com.br/shared/env/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py" in execute_sql
  784.         cursor = self.connection.cursor()
File "/home/sieve/sitroom.sieve.com.br/shared/env/local/lib/python2.7/site-packages/django/db/backends/__init__.py" in cursor
  163.         self.validate_thread_sharing()
File "/home/sieve/sitroom.sieve.com.br/shared/env/local/lib/python2.7/site-packages/django/db/backends/__init__.py" in validate_thread_sharing
  515.                 % (self.alias, self._thread_ident, thread.get_ident()))

Exception Type: DatabaseError at /
Exception Value: DatabaseWrapper objects created in a thread can only be used in that same thread. The object with alias 'default' was created in thread id 140049505195808 and this is thread id 61130224.

Here is my gunicorn.conf.py:

##
# Gunicorn config at 
# Managed by Chef - Local Changes will be Nuked from Orbit (just to be sure)
##

# What ports/sockets to listen on, and what options for them.
bind = "127.0.0.1:9300"

# The maximum number of pending connections
backlog = 2048

# What the timeout for killing busy workers is, in seconds
timeout = 300

# How long to wait for requests on a Keep-Alive connection, in seconds
keepalive = 2

# The maxium number of requests a worker will process before restarting
max_requests = 1024

# Whether the app should be pre-loaded
preload_app = True

# How many worker processes
workers = 16

# Type of worker to use
worker_class = "gevent"

# The granularity of error log outputs.
loglevel = "error"

The error occurs every time, just accessing any URL of the django app (that depends on any model, of course) triggers this error. Any ideas? Since changing to gunicorn-18.0 solves the problem, I'm assuming that gunicorn-19.x is doing something different.

If you need any additional information, let me know and I will post it here.

For now I'm using 18.0.

Thanks a lot.

[gukoff]

I am stumbling upon this issue with gunicorn==18.0. In the gunicorn_conf.py I have worker_class = 'gevent', preload_app = True and custom pre_fork, on_starting and on_reload functions.

Putting these lines on top of the gunicorn_conf.py file seems to solve the issue for me:

import gevent.monkey
gevent.monkey.patch_thread()

---

Update: I've had these lines in my gunicorn.conf. Getting rid of them solved the issue without monkey-patching.

import django
django.setup()

Because of them django initiated the connection before gunicorn's monkey-patching.

[FraBle]

@gukoff proposed fix didn't work for me, I still get the same error 😞

[tilgovi]

I'm going to close this and open a discussion with the mailing list label on the R20 milestone for monkey-patching the arbiter in gevent. If you are having problems related to anything in this discussion and you think it might be a bug in Gunicorn, please open an issue. You can mention this one by number, or link to comments, if it helps add context, but at this point this is an old ticket with conversations in parallel about several versions of Gunicorn and different symptoms.

[aminabbasov]

I would like to note that as of 2024, this problem persists. I encountered a similar issue at work, and the problem was resolved by removing the --reload flag. Therefore, if you are experiencing this error and using this flag, consider deleting it as it may solve your issue :neckbeard: