我在通过 mod_wsgi 在 linux 机器上运行的 Python 2.7 上运行 SQL Alchemy 0.8.1 时遇到问题。 它有时会产生“InvalidRequestError:此 session 处于‘准备’状态；在此事务中无法发出进一步的 SQL”。
下面是错误的详细堆栈跟踪:
...
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2173, in one
ret = list(self)
self = <sqlalchemy.orm.query.Query object at 0x7f6f64348dd0>
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2216, in __iter__
return self._execute_and_instances(context)
self = <sqlalchemy.orm.query.Query object at 0x7f6f64348dd0>
context = <sqlalchemy.orm.query.QueryContext object at 0x7f6f64348d50>
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2229, in _execute_and_instances
close_with_result=True)
querycontext = <sqlalchemy.orm.query.QueryContext object at 0x7f6f64348d50>
self = <sqlalchemy.orm.query.Query object at 0x7f6f64348dd0>
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2220, in _connection_from_session
**kw)
self = <sqlalchemy.orm.query.Query object at 0x7f6f64348dd0>
kw = {'clause': , 'close_with_result': True, 'mapper': }
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 798, in connection
close_with_result=close_with_result)
mapper =
clause = <sqlalchemy.sql.expression.Select at 0x7f6f64348d90; Select object>
self = <sqlalchemy.orm.session.Session object at 0x7f6f68f6fe50>
kw = {}
bind = Engine(mysql+mysqldb://xxx:yyy@localhost/zzz?charset=utf8)
close_with_result = True
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 802, in _connection_for_bind
return self.transaction._connection_for_bind(engine)
engine = Engine(mysql+mysqldb://xxx:yyy@localhost/zzz?charset=utf8)
self = <sqlalchemy.orm.session.Session object at 0x7f6f68f6fe50>
kwargs = {'close_with_result': True}
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 281, in _connection_for_bind
self._assert_active()
bind = Engine(mysql+mysqldb://xxx:yyy@localhost/zzz?charset=utf8)
self = <sqlalchemy.orm.session.SessionTransaction object at 0x7f6f69be8050>
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 181, in _assert_active
"This session is in 'prepared' state; no further "
rollback_ok = False
prepared_ok = False
closed_msg = 'This transaction is closed'
self = <sqlalchemy.orm.session.SessionTransaction object at 0x7f6f69be8050>
InvalidRequestError: This session is in 'prepared' state; no further SQL can be emitted within this transaction.
此错误是随机发生的 - 可能需要几天时间才能看到，也可能会在 5 分钟后发生。我不明白是什么导致了这个问题和最大的问题——我不明白这个错误是什么意思。什么是“准备”状态？文档没有关于此状态的信息。据我所知，它与双向交易有一定关系，但我没有在我的代码中使用它们。我使用 Session.query 和 Session.commit。
如有任何帮助，我们将不胜感激。
请您参考如下方法:
我真的在这里猜测，但我认为也许您正在使用 wsgi 部署的线程，并且您的 session 实例不是线程本地的。您当然可以这样做，只需按照官方文档中的这个简短教程操作即可:
