Elixir - Threading issue

[yoav glazner]

Hi,

I have a problem in my program, i can replacte it this way:

<code>

from elixir import *

class Job(Entity):

  number = Field(Integer)

def f(job):

  job.expire()

  job.number

metadata.bind = "oracle://user:password@db"

setup_all()

job = Job.query.get(1) #number is primary key

thread.start_new(f,(job,))

thread.start_new(f,(job,))

time.sleep(4)

</code>

ok now i get this:

AttributeError: expired_attributes

how should i approch this?

(I know that if i put a lock on function "f" it doesn't happen...)

Many Thanks,

Yoav Glazner

[Diez B. Roggisch]

Please post the full traceback.

Diez

[yoav glazner]

Please post the full traceback.

Unhandled exception in thread started by <function f at 0x01049A30>

Traceback (most recent call last):

  File "C:\Test\src\elxOra.py", line 21, in f

    job.number

  File "C:\Python26\lib\site-packages\sqlalchemy-0.5.4p2-py2.6.egg\sqlalchemy\orm\attributes.py", line 158, in __get__

    return self.impl.get(instance_state(instance), instance_dict(instance))

  File "C:\Python26\lib\site-packages\sqlalchemy-0.5.4p2-py2.6.egg\sqlalchemy\orm\attributes.py", line 374, in get

    value = callable_()

  File "C:\Python26\lib\site-packages\sqlalchemy-0.5.4p2-py2.6.egg\sqlalchemy\orm\state.py", line 175, in __call__

    del self.expired_attributes

AttributeError: expired_attributes 

[Gaetan de Menten]

As far as I know, you shouldn't share a particular object instance
between several threads.

The answer to the question: "Is the session thread-safe?" in:

http://www.sqlalchemy.org/docs/session.html#frequently-asked-questions

applies to your case. But you can perfectly load the same row in two
different threads... If both threads can write, you'll have to
implement some kind of synchronisation mechanism though.

--
Gaëtan de Menten

[yoav glazner]

If one thread can only read then this should be safe?

def f(jobNumber):

   job = Job.get(jobNumber)
   job.expire()
   job.number

(f is a threaded function ...)

I can't test this now since i don't have a DB here =(

[Diez B. Roggisch]

Looks good, yes.

Diez

[yoav glazner]

Looks good, yes.

Stop me if I'm asking too much, but.

will this work because:

 job = Job.get(jobNumber) #will be a newly created object, not the one from the identity-map

Thank you and Gaëtan for the answers

[yoav glazner]

On Mon, Jun 21, 2010 at 11:25 PM, yoav glazner <yoavg...@gmail.com> wrote:

Looks good, yes.

Stop me if I'm asking too much, but.

will this work because:

 job = Job.get(jobNumber) #will be a newly created object, not the one from the identity-map

ok, checked it myself, it seems it brings a fresh object since if i do id(job) it brigs a new address.