Question

I’ve deployed a django app with a multithreading module to dotcloud.
This thread is putting some slow stuff to DB (usually it takes about 3-5 seconds).

When I test it in my virtual enviornment – all works fine.

Here is my dotcloud.yml:

www:
  type: python
  config:
    python_version: v2.7
    uwsgi_enable_threads: true
db:
  type: postgresql
data:
  type: mongodb

Here is my dotcloud log:

[www.0] Process Process-1:
[www.0] Traceback (most recent call last):
[www.0]   File "/usr/lib/python2.7/multiprocessing/process.py", line 258, in _bootstrap
[www.0]     self.run()
[www.0]   File "/usr/lib/python2.7/multiprocessing/process.py", line 114, in run
[www.0]     self._target(*self._args, **self._kwargs)
[www.0]   File "/home/dotcloud/current/usn/views.py", line 416, in sync_countdown
[www.0]     put_current_data_to_db(user_name)
[www.0]   File "/home/dotcloud/current/usn/views.py", line 429, in put_current_data_to_db
[www.0]     current_client = Client.objects.get(user_name=user_name)
[www.0]   File "/home/dotcloud/env/local/lib/python2.7/site-packages/django/db/models/manager.py", line 131, in get
[www.0]     return self.get_query_set().get(*args, **kwargs)
[www.0]   File "/home/dotcloud/env/local/lib/python2.7/site-packages/django/db/models/query.py", line 361, in get
[www.0]     num = len(clone)
[www.0]   File "/home/dotcloud/env/local/lib/python2.7/site-packages/django/db/models/query.py", line 85, in __len__
[www.0]     self._result_cache = list(self.iterator())
[www.0]   File "/home/dotcloud/env/local/lib/python2.7/site-packages/django/db/models/query.py", line 291, in iterator
[www.0]     for row in compiler.results_iter():
[www.0]   File "/home/dotcloud/env/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 763, in results_iter
[www.0]     for rows in self.execute_sql(MULTI):
[www.0]   File "/home/dotcloud/env/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 818, in execute_sql
[www.0]     cursor.execute(sql, params)
[www.0]   File "/home/dotcloud/env/local/lib/python2.7/site-packages/django/db/backends/util.py", line 40, in execute
[www.0]     return self.cursor.execute(sql, params)
[www.0]   File "/home/dotcloud/env/local/lib/python2.7/site-packages/django/db/backends/postgresql_psycopg2/base.py", line 52, in execute
[www.0]     return self.cursor.execute(query, args)
[www.0] DatabaseError: server closed the connection unexpectedly
[www.0]     This probably means the server terminated abnormally
[www.0]     before or while processing the request.

Answer 1

Common way to resolve issues with databases in django threads worked for me – i’ve just added:

django.db.connection.close()

before starting my thread

Short explanation:

Then django forks new thread, the child uses the same connection to DB, as a parent.

If we close the connection, a child will create a new one.