if you can at least share the stack trace that should tell a lot
On Mon, Feb 26, 2018 at 3:05 PM, Mike Bayer <mike...@zzzcomputing.com> wrote:
> On Mon, Feb 26, 2018 at 2:54 PM, Cecil Rock <cecil.r...@gmail.com> wrote:
>> Hi,
>>
>> I have a question about some ORM internal state tracking stuff. If this
>> isn't the right venue for this type of question my apologies.
>>
>> I've run into what looks like a race condition using the ORM during some our
>> production workloads. I am trying to figure out if our code has a bug or if
>> we are hitting a bug inside the ORM. We are occasionally getting a
>> FlushError with this message "Over 100 subsequent flushes have occurred
>> within session.commit() - is an after_flush() hook creating new objects?"(
>> we are not using any event hooks.)
>>
>> I've managed to track this down to what looks like the session.identity_map
>> has an InstanceState in its modified list (i.e. the session is dirty) but
>> the InstanceState is not in the sessions.identity_map._dict (i.e not in the
>> session?). The InstanceState is showing that it is attached to the session.
>>
>> e.g. the WeakInstanceDict looks like this for the session...
>> _dict = {} # is empty
>> _modified = ( TheModifiedInstanceState )
>>
>>
>> This is a difficult bug to reproduce, but seems more likely to occur if we
>> hold the session open longer like so...
>>
>> my_model = MyModel.query.filter('...').first()
>> my_model.attr = 'something'
>> sleep(1)
>> session.commit() <-- flush error "occasionally"
>>
>>
>> I was hoping someone could confirm for me that this is "never a valid state"
>> for the identity map to be in. (Or if I'm super lucky someone will
>> recognize this as a known bug or something).
>
> try doing a gc.collect() there instead of a sleep since it looks
> related to the object being garbage collected.
>
> but no, that is never a valid state and I cannot imagine how you would
> get that error without using any flush hooks. that error was put in
> after observing very specifically end-user event hooks that would add
> more things to the dirty state within the scope of a flush. There is
> no way that can happen otherwise.
>
>
>
>
>>
>> Thanks for the help,
>>
>> Cecil
>>
>> --
>> SQLAlchemy -
>> The Python SQL Toolkit and Object Relational Mapper
>>
>> http://www.sqlalchemy.org/
>>
>> To post example code, please provide an MCVE: Minimal, Complete, and
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>> description.
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--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
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