Question

我在Django中有一个简单的测试用例失败：

模型（app / models.py）：

from django.db import models
class M(models.Model):
    condition = models.CharField(max_length=80, db_index=True)

测试（app / tests.py）：

from django.test import TestCase
import threading
import time
from app.models import M

def insert():
    time.sleep(0.3)
    ua = M(condition='x')
    ua.save()

class DjangoRaceTest(TestCase):
    def test_parallel(self):
        insert()  # <--- works
        #threading.Thread(target=insert).start()  # <-- fails

        for i in range(10):
            count = M.objects.all()
            if count:
                return True
            time.sleep(0.1)

        assert count

上面的代码通过;但是如果我注释掉插入的直接调用而不是取消注释线程调用，则断言失败，我得到：

Creating test database for alias 'default'...
Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/lib/python2.6/threading.py", line 532, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.6/threading.py", line 484, in run
    self.__target(*self.__args, **self.__kwargs)
  File "/home/jacobsen/testdjango/app/tests.py", line 10, in insert
    ua.save()
  File "/home/jacobsen/dj14/lib/python2.6/site-packages/Django-1.4-py2.6.egg/django/db/models/base.py", line 463, in save
    self.save_base(using=using, force_insert=force_insert, force_update=force_update)
  File "/home/jacobsen/dj14/lib/python2.6/site-packages/Django-1.4-py2.6.egg/django/db/models/base.py", line 551, in save_base
    result = manager._insert([self], fields=fields, return_id=update_pk, using=using, raw=raw)
  File "/home/jacobsen/dj14/lib/python2.6/site-packages/Django-1.4-py2.6.egg/django/db/models/manager.py", line 203, in _insert
    return insert_query(self.model, objs, fields, **kwargs)
  File "/home/jacobsen/dj14/lib/python2.6/site-packages/Django-1.4-py2.6.egg/django/db/models/query.py", line 1576, in insert_query
    return query.get_compiler(using=using).execute_sql(return_id)
  File "/home/jacobsen/dj14/lib/python2.6/site-packages/Django-1.4-py2.6.egg/django/db/models/sql/compiler.py", line 910, in execute_sql
    cursor.execute(sql, params)
  File "/home/jacobsen/dj14/lib/python2.6/site-packages/Django-1.4-py2.6.egg/django/db/backends/sqlite3/base.py", line 337, in execute
    return Database.Cursor.execute(self, query, params)
DatabaseError: no such table: app_m

显然有一些Django魔法在这里让我失望，或者......某事？我已经在OS X，Ubuntu 10.04，Django 1.2和1.4的各种组合上进行了测试。

Answer 1

答案似乎是在内存中，sqlite数据库不能跨线程共享。

This is a bug report from 1.1核心开发人员认为它不是基于SQLAlchemy's lack of support的错误（在没有来自sqlite引用的其他直接信息的情况下）：

Pysqlite连接不支持在线程之间移动，除非check_same_thread Pysqlite标志设置为False。在另外，在使用内存中的SQLite数据库时，还要使用完整的数据库仅存在于单个连接的范围内。据报道内存数据库不支持在它们之间共享线程无论check_same_thread标志 - 这意味着a 多线程应用程序无法共享来自：memory：database的数据跨线程，除非访问连接仅限于一个工作线程通过排队机制进行通信并发线程。

奇怪的Django行为与DB插入来自单独的线程

1 个答案: