Hi all,
I'm using Python 2.5.1 with SqlAlchemy 0.5rc2 with Sqlite on Windows
Server 2003 and I'm having a problem with my application throwing
InvalidRequestError and ConcurrentModification exceptions. Here is my
simplified declarative class:
class Job(srsmanagerdb.Base):
STATUS_INIT = 0
STATUS_RUN = 1
STATUS_DONE = 2
STATUS_FAIL = 3
__tablename__ = "jobs"
id = Column(Integer, primary_key=True,
autoincrement=True)
nas = Column(String(12), default=None)
filename = Column(String(64), default=None, index=True)
filesize = Column(Integer, default=None)
created = Column(DateTime, default=None)
job_id = Column(String(32), default=None)
productType = Column(String(1), default=None)
contentType = Column(String(10), default=None)
priorityType = Column(String(10), default=None)
priority = Column(Integer, default=None)
assignedPress = Column(Integer, default=None)
status = Column(Integer, default=None)
def __init__(self, objrefs, fileDetails):
nas, filename, filesize, ctime = fileDetails
self.nas = nas
self.filename = filename
self.filesize = filesize
self.created =
datetime.datetime(*time.strptime(ctime[:ctime.find(".")], "%Y-%m-%d %H:
%M:%S")[0:6])
This object is used to track state information about jobs being
handled by a looping state machine. I keep a list of all active jobs
in a Jobs collection class, so there are many active intances of the
above class. The simplified Jobs collection class looks like this:
class Jobs(AppContext):
def __init__(self, objrefs):
self._logger = __logger__
self._jobs = []
self._markedForRemoval = []
def markForRemoval(self, job):
self._markedForRemoval.append(job)
def removeMarkedJobs(self): # throws exception in
here
session = srsmanagerdb.Session()
for markedJob in self._markedForRemoval:
try:
session.expire_all()
session.delete(markedJob)
session.commit()
self._jobs.remove(markedJob)
except sqlalchemy.exceptions.ConcurrentModificationError,
e:
self._logger.warn("%s threw exception %s" %
(job.filename, e))
self._markedForRemoval = []
def process(self):
for job for self._jobs:
job.process()
if job.status == Job.STATUS_DONE:
self.markForRemoval(job)
self.removeMarkedJobs()
The above simplified code runs for awhile (10s of minutes) with
hundreds of jobs and then it throws the exception below in the
removeMarkedJobs() method. I've worked really hard trying to figure
out what's going wrong here. This is the only place where I delete
jobs and commit that delete to the database. One question I have is if
it's a good idea to keep a list of active Job instances (database
rows) in a Python list. In my removeMarkedJobs() I'm deleting the job
instances, and then removing the job instance from the list. Is this
necessary or good practice? I haven't figured out if just deleting the
job instance from the list (self._jobs.remove(markedJob)) will also
delete the job from the database or not. Anyway, here's the traceback
of the exception I'm getting. Any help would be appreciated.
Thanks, Doug
2008-10-27 18:15:54 srsmanager ERROR unexpected error,
restarting: Traceback (most recent call last):
File "c:\cygwin\home\ripadmin\dev\srsmanager\srsprocess.py", line 154,
in runjobs isActive = self._jobs.process()
File "c:\cygwin\home\ripadmin\dev\srsmanager\jobs.py", line 436, in
process self.removeMarkedJobs()
File "c:\cygwin\home\ripadmin\dev\srsmanager\jobs.py", line 397, in
removeMarkedJobs self._logger.warn("%s threw exception %s" %
(markedJob.filename, e))
File "c:\python\2.5\lib\site-packages\SQLAlchemy-0.5.0rc1-py2.5.egg
\sqlalchemy\orm\attributes.py", line 135, in __get__ return
self.impl.get(instance_state(instance))
File "c:\python\2.5\lib\site-packages\SQLAlchemy-0.5.0rc1-py2.5.egg
\sqlalchemy\orm\attributes.py", line 327, in get value =
callable_()
File "c:\python\2.5\lib\site-packages\SQLAlchemy-0.5.0rc1-py2.5.egg
\sqlalchemy\orm\attributes.py", line 909, in __call__
attr.impl.key in unmodified
File "c:\python\2.5\lib\site-packages\SQLAlchemy-0.5.0rc1-py2.5.egg
\sqlalchemy\orm\mapper.py", line 1715, in _load_scalar_attributes
result = session.query(mapper)._get(identity_key, refresh_state=state,
only_load_props=attribute_names)
File "c:\python\2.5\lib\site-packages\SQLAlchemy-0.5.0rc1-py2.5.egg
\sqlalchemy\orm\query.py", line 1211, in _get return q.all()[0]
File "c:\python\2.5\lib\site-packages\SQLAlchemy-0.5.0rc1-py2.5.egg
\sqlalchemy\orm\query.py", line 985, in all return list(self)
File "c:\python\2.5\lib\site-packages\SQLAlchemy-0.5.0rc1-py2.5.egg
\sqlalchemy\orm\query.py", line 1073, in __iter__ return
self._execute_and_instances(context)
File "c:\python\2.5\lib\site-packages\SQLAlchemy-0.5.0rc1-py2.5.egg
\sqlalchemy\orm\query.py", line 1076, in _execute_and_instances
result = self.session.execute(querycontext.statement,
params=self._params, mapper=self._mapper_zero_or_none(),
_state=self._refresh_state)
File "c:\python\2.5\lib\site-packages\SQLAlchemy-0.5.0rc1-py2.5.egg
\sqlalchemy\orm\session.py", line 750, in execute return
self.__connection(engine, close_with_result=True).execute( File "c:
\python\2.5\lib\site-packages\SQLAlchemy-0.5.0rc1-py2.5.egg\sqlalchemy
\orm\session.py", line 717, in __connection return
self.transaction._connection_for_bind(engine)
File "c:\python\2.5\lib\site-packages\SQLAlchemy-0.5.0rc1-py2.5.egg
\sqlalchemy\orm\session.py", line 309, in _connection_for_bind
self._assert_is_active()
File "c:\python\2.5\lib\site-packages\SQLAlchemy-0.5.0rc1-py2.5.egg
\sqlalchemy\orm\session.py", line 244, 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
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