If it's necessary I will provide both, the question before that is: 
Should ZopeTransactionExtension work with ShardedSession? Because if it 
wasn't designed for that, then there's no need to write test cases.

Best regards

W dniu wtorek, 4 grudnia 2012 16:31:16 UTC+1 użytkownik Michael Bayer 
napisał:
>
> 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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