OK what's idm_rw.py, and is it the only module in the app that specifies a table named "attribute_config"? is idm_rw.py always imported right when the app starts up? or is there some kind of loading going on ?
On Oct 21, 2013, at 9:51 PM, Joseph Casale <jcas...@gmail.com> wrote:
> Hey Michael,
> For reasons beyond my control at the moment, logging was utterly butchered in
> a completely
> incomprehensible means by another developer.
>
> Traceback (most recent call last):
> File "D:\app_folder\plugin\idm_rw.py", line 6, in <module>
> from idm_config import Attribute, Session
> File "D:\app_folder\include\idm_config.py", line 478, in <module>
> class PortalConfig(Base, EnvironmentMixin):
> File "D:\Python33\lib\site-packages\sqlalchemy\ext\declarative\api.py",
> line 50, in __init__
> _as_declarative(cls, classname, cls.__dict__)
> File "D:\Python33\lib\site-packages\sqlalchemy\ext\declarative\base.py",
> line 222, in
> _as_declarative **table_kw)
> File "D:\Python33\lib\site-packages\sqlalchemy\schema.py", line 319, in
> __new__ "existing Table object." % key)
>
> sqlalchemy.exc.InvalidRequestTable 'attribute_config' is already
> defined for this MetaData instance. Specify 'extend_existing=True' to
> redefine
> options and columns on an existing Table object.
>
> I think thats what it looked like before he had his way:)
>
> Thanks!
> jlc
>
>
> On Mon, Oct 21, 2013 at 3:25 PM, Michael Bayer <mike...@zzzcomputing.com>
> wrote:
> how about a stack trace?
>
>
> On Oct 21, 2013, at 4:11 PM, Joseph Casale <jcas...@gmail.com> wrote:
>
>> Hi Michael,
>> I spoke with the developer of the application that launches the plugins I am
>> writing and each
>> python script is run by starting an entirely new process with the
>> interpreter and each plugin.
>>
>> It should be a clean environment. From the plugins, I simply import which
>> ever tables from
>> the module below that I would need.
>>
>> In the event I am doing something wrong, my code looks like:
>>
>> from os import path
>> from sqlalchemy import (
>> Column, CheckConstraint, DDL, ForeignKey, Index, Integer, String,
>> create_engine, event
>> )
>> from sqlalchemy.engine import Engine
>> from sqlalchemy.ext.declarative import declared_attr, declarative_base
>> from sqlalchemy.orm import sessionmaker
>>
>>
>> db_name = path.join('path', 'config', 'sqlite.db')
>> engine = create_engine('sqlite:///{}'.format(db_name), echo=False)
>> Session = sessionmaker(bind=engine, autoflush=False, autocommit=False)
>> Base = declarative_base()
>>
>>
>> @event.listens_for(Engine, 'connect')
>> def set_sqlite_pragma(dbapi_connection, connection_record):
>> cursor = dbapi_connection.cursor()
>> cursor.execute('PRAGMA foreign_keys=ON')
>> cursor.close()
>>
>>
>> table defs...
>>
>>
>> if __name__ == '__main__':
>> Base.metadata.create_all(engine)
>>
>>
>> Thanks so much for the help,
>> jlc
>>
>>
>> On Sun, Oct 20, 2013 at 11:01 PM, Michael Bayer <mike...@zzzcomputing.com>
>> wrote:
>> the MetaData object holds one Table object per unique name given. If you
>> use the Table constructor more than once with the same name and the same
>> MetaData, you get this error.
>>
>> That's how the error is caused, then the fact that the error is "occasional"
>> points strongly to a race condition of some kind, more than one thread both
>> calling the constructor for Table with the same name. Patterns that could
>> cause this could be some kind of unsynchronized global registry or singleton
>> object that when called produces a new Table object.
>>
>> The recommended pattern is for Table objects (as well as mapped classes) to
>> generally be declared at the module level so that these names are produced
>> only at module import time, which itself should occur before the application
>> starts any threads in addition to the main application thread.
>>
>>
>>
>>
>> On Oct 20, 2013, at 11:04 PM, Joseph Casale <jcas...@gmail.com> wrote:
>>
>>> I have a module that is imported by several Python scripts run by an
>>> application
>>> that fires up a new interpreter session for each invocation. When not under
>>> load or
>>> running the code manually at the cli things work fine but once the
>>> concurrency
>>> raises and the application starts seeing some load it emits
>>> InvalidRequestError
>>> exceptions on one table.
>>>
>>> After searching I am not sure the results relate to my issue or maybe my
>>> lack
>>> of familiarity with SQLAlchemy has the better of me.
>>>
>>> Any guidance would be greatly appreciated,
>>> jlc
>>>
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>>
>>
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>
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