Hello,
Is there a way to use ZopeTransactionExtension using ShardedSession? I just
cannot figure it out. When I use it then I'm getting exception during any
query:
unbound method after_begin() must be called with ZopeTransactionExtension
instance as first argument (got SessionMaker instance instead)
Best regards
W dniu środa, 28 grudnia 2011 18:18:46 UTC+1 użytkownik Michael Bayer
napisał:
>
>
> On Dec 27, 2011, at 11:58 PM, Josh Ha-Nyung Chung wrote:
>
> I've made web application using Pyramid 1.2.5 + Python 2.7.1 + SQLAlchemy
> 0.7.4 and occasionally encountered the following error.
>
> File "build/bdist.linux-x86_64/egg/sqlalchemy/engine/base.py", line
> 1599, in _execute_context
> conn = self._revalidate_connection()
> File "build/bdist.linux-x86_64/egg/sqlalchemy/engine/base.py", line
> 1018, in _revalidate_connection
> "Can't reconnect until invalid "
> StatementError: Can't reconnect until invalid transaction is rolled back
> (original cause: InvalidRequestError: Can't reconnect until invalid
> transaction is rolled back) 'SELECT dp_user.user_id AS dp_user_user_id,
> dp_user.email AS dp_user_email, dp_user.new_email AS dp_user_new_email,
> dp_sns_user.`SNS_name` AS `dp_sns_user_SNS_name` \\nFROM dp_user,
> dp_sns_user \\nWHERE dp_user.status = %s AND dp_user.user_id =
> dp_sns_user.user_id AND dp_user.signup_date >= %s AND dp_user.signup_date <
> %s ORDER BY dp_user.signup_date DESC' [immutabledict({})]
>
> All queries what my web app is doing is SELECT. So I don't think I need to
> explicitly call session.commit() at all. I can't understand why "invalid
> transaction" ever occurred.
> mysqld's wait_timeout is 28800 and I create sqlalchemy engine with
> pool_recycle of 3600.
>
> after I restarted apache, which run my web app through wsgi, it starts
> working again.
>
>
>
> this can only happen if an error is emitted from a query or other SQL
> operation inside of a transaction, and the connection continues to be
> reused subsequent to that error condition without any attendance being
> given to the invalid transaction.
>
> The "restarting of apache" step as the only solution suggests you're
> sharing a single transaction between multiple requests, and the error was
> emitted in a previous request. You'd need to ensure that the Session is
> completely closed out at the end of each request, or at least rollback() is
> called, so that any remaining transactional state is released. Pyramid
> suggests integrating with the ZopeTransactionExtension which I believe
> should handle this (you should check on the Pyramid list).
>
>
>
>
>
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