On Wed, Feb 21, 2018 at 2:34 PM, Stefan Schwarzer
<sschwar...@sschwarzer.net> wrote:
> Thanks for the quick reply!
>
> On Wednesday, February 21, 2018 at 6:44:33 PM UTC+1, Mike Bayer wrote:
>>
>> I can come up with other things that can break based on the idea that
>> you're doing a full connection + execute sequence within the log
>> handler deep within that engine's own processes, such as, it can cause
>> connection pool exhaustion when you're working with the last
>> connection available, then your logger has no connection, it goes to
>> get one and...hang. I can reproduce this with your script (set
>> pool_size=1, max_overflow=0, set up logging and run an execute() so it
>> actually logs, and it hangs for 30 seconds until the timeout and
>> crashes, see stack trace below), so your approach is not safe in any
>> case.
>
>
> Thanks for the clarification.
>
>>
>> It would be a lot simpler and robust if your log handler just used its
>> own Engine (make a new one from the engine.url you already have).
>
>
> Good idea.
>
>>
>> That way you can lose all that re-entrant mutex stuff too.
>
>
> The mutex stuff is there because in the actual code SQLAlchemy logging is
> switched on and I want to prevent that SQLAlchemy tries to log the insert
> statement in `_emit`. I didn't think of this when I posted the original
> question, so I could have left out the mutex stuff for the sake of the
> example code.
but it wont, if you disable your logger engine from actually logging:
from sqlalchemy import create_engine
import logging
logging.basicConfig()
logging.getLogger("sqlalchemy.engine").setLevel(logging.INFO)
e = create_engine("sqlite://")
e.scalar("select 1")
print("no more logging")
e = create_engine("sqlite://", logging_name="log_only")
logging.getLogger("sqlalchemy.engine.base.Engine.log_only").setLevel(logging.WARN)
e.scalar("select 1")
the ".base" module in the path there is slightly non-standard but
shouldn't be changing anytime soon.
>
> Best regards,
> Stefan
>
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> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
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SQLAlchemy -
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http://www.sqlalchemy.org/
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