I've learned a bit more. Apparently the sqlite database occasionally
gets locked by another process and that lock lasts longer than the
five second default timeout. SQL Alchemy quietly issues a ROLLBACK,
but doesn't say anything more about it. The result is that the
session is no longer active and eventually produces the error I
mentioned above. Here are the log messages showing the insert failing
after the five second default timeout.
2009-04-28 15:10:48,118 INFO sqlalchemy.engine.base.Engine.0x...ae70
INSERT INTO table ("id", "value") VALUES (?, ?)
2009-04-28 15:10:48,118 INFO sqlalchemy.engine.base.Engine.0x...ae70
[1, 'my value']
2009-04-28 15:10:53,148 INFO sqlalchemy.engine.base.Engine.0x...ae70
ROLLBACK
Is there some way to configure SQL Alchemy to raise an exception when
it issues the rollback, or when it finds the database locked? It's a
bit confusing to see a ROLLBACK with no indication of why (and if I
didn't know that the sqlite3 default timeout was five seconds, I might
still be scratching my head).
Meanwhile, my application works with an increased timeout, but that
may change when the system is under high load.
Thanks for your input...
On Apr 28, 6:27 pm, Michael Bayer <[email protected]> wrote:
> squelching typically means one of two things.
>
> either you're doing this:
>
> try:
> # do stuff with session
> except:
> print "error !"
> # .. keep going
>
> or, you are allowing concurrent access to a single session with
> multiple threads, one of your threads is throwing an exception
> (usually due to the corrupted state of the session, since the session
> is not mutexed) and the other thread gets this error.
>
> On Apr 28, 2009, at 4:53 PM, Daniel wrote:
>
>
>
> > Hello,
>
> > In my application I have a function that looks more or less like this
>
> > def run(self):
> > # process first object in sequence
> > for firstObject in firstObjects:
> > self.session.add(firstObject)
> > self.session.commit()
>
> > # process second object in sequence
> > # lots of these, so break along the way
> > count = 0
> > for secondObject in secondObjects:
> > self.session.add(secondObject)
> > count += 1
> > if (count > 100):
> > #**********************************
> > self.session.commit()
> > #**********************************
> > count = 0
> > time.sleep(1) # pause to let other process access
> > the db
> > self.session.commit()
>
> > # process third objects
> > for thirdObject in thirdObjects:
> > self.session.add(thirdObject)
> > self.session.commit()
>
> > The commit nested inside the second loop (highlighted by asterisks) is
> > potentially called many times (occasionally there are thousands of
> > objects to deal with). intermittently that commit will produce the
> > following error:
>
> > Traceback (most recent call last):
> > File "C:\Aptina\pop\tester\AptinaStagingService.py", line 106, in
> > __init__
> > self.run(self.pushPath,self.stagingPath)
> > File "C:\Aptina\pop\tester\AptinaStagingService.py", line 231, in
> > run
> > self.session.commit()
> > File "c:\python25\Lib\site-packages\sqlalchemy\orm\session.py", line
> > 673, in commit
> > self.transaction.commit()
> > File "c:\python25\Lib\site-packages\sqlalchemy\orm\session.py", line
> > 378, in commit
> > self._prepare_impl()
> > File "c:\python25\Lib\site-packages\sqlalchemy\orm\session.py", line
> > 351, in _prepare_impl
> > self._assert_is_active()
> > File "c:\python25\Lib\site-packages\sqlalchemy\orm\session.py", line
> > 247, in _assert_is_active
> > "The transaction is inactive due to a rollback in a "
> > InvalidRequestError: The transaction is inactive due to a rollback in
> > a subtransaction. Issue rollback() to cancel the transaction.
>
> > I've read elsewhere in this group (http://groups.google.com/group/
> > sqlalchemy/browse_thread/thread/b87af73232998fe4) about this error
> > message, but I'm not sure what they mean by "squelching the original
> > exception somewhere". Can someone please help me understand why I'm
> > getting this error and ideas on how to fix it.
>
> > Thanks.
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