sqlite3 “OperationalError: no such table” on threaded operation

from django.db import models

# Super-simple model
class MyModel(models.Model):
message = models.CharField('Message', max_length=200, blank=True)

#Test
from django.test import TestCase

import time
import threading
import random


done = threading.Event()
nThreads = 1


def InsertRec(msg):
rec = MyModel.objects.create(message=msg)
rec.save()


def InsertThread():
try:
msgNum = 1
thrName = threading.currentThread().name
print 'Starting %s' % thrName
while not done.wait(random.random() * 0.1):
msgNum += 1
msg = '%s: %d' % (thrName, msgNum)
print msg
InsertRec(msg)
finally:
done.set()
pass


class ThreadTestRun(TestCase):

def testRunIt(self):
nThisThread = 10
msgSet = set()
for x in xrange(nThisThread):
msg = 'Some message %d' % x
InsertRec(msg) # From main thread: works!
msgSet.add(msg)
self.assertEqual(MyModel.objects.count(), nThisThread)
# We use sets because .all() doesn't preserve the original order.
self.assertEqual(msgSet, set([r.message for r in MyModel.objects.all()]))
thrSet = set()
for thrNum in xrange(nThreads):
t = threading.Thread(name='Thread %d' % thrNum, target=InsertThread)
t.start()
thrSet.add(t)

done.wait(10.)
done.set()
for t in thrSet:
t.join()

By everything I read in the docs, both Django and py-sqlite3 should be fine with threaded access. (Right?) But the attached code snippet fails for me. The operations in the main thread work, but not in the thread(s) I create. There I get:

File "C:\Python27\lib\site-packages\django-1.9-py2.7.egg\django\db\backends\sq lite3\base.py", line 323, in execute return Database.Cursor.execute(self, query, params)

OperationalError: no such table: thrtest_mymodel

What's the problem?

How do I go about tracking down exactly what's happening? The point of failure in Django is pretty indimidating. I can't tell how to see what tables it DOES see, or what differences to look for between main and other threads.

Here is DATABASES from settings.py:

DATABASES = {      'default': {          'ENGINE': 'django.db.backends.sqlite3',          'NAME': ':memory:', # os.path.join(BASE_DIR, 'db.sqlite3'),          'TEST_NAME' : ':memory:',      },  }

With respect to Django's ticket #12118, I get the same symptoms using ':memory:' or a disk file (for TEST_NAME).

Django 1.9, Python 2.7.11.

Posted yesterday on stackoverflow.

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