test cases and stack traces would be a start
On Dec 4, 2012, at 9:29 AM, Piotr Deszyński wrote:
> 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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