Filed it at https://bugs.launchpad.net/taskflow/+bug/1559496
Thanks,
Kanthi
On Sat, Mar 19, 2016 at 9:30 PM, Joshua Harlow <harlo...@fastmail.com>
wrote:
> Interesting error, that could be a bug and perhaps we should ensure
> upgrade is more thread-safe (with a lock on upgrade); can u open a bug @
> bugs.launchpad.net/taskflow for that and we can try to add said lock
> (that should hopefully resolve what u are seeing, although if it doesn't
> then the bug lies somewhere else).
>
> Thanks much!
>
> -Josh
>
>
> On 03/19/2016 08:45 AM, pnkk wrote:
>
>> Hi Joshua,
>>
>> Thanks for all your inputs.
>> We are using this feature successfully. But I rarely see an issue
>> related to concurrency.
>>
>> To give you a brief, we use eventlets and every job runs in a separate
>> eventlet thread.
>>
>> In the job execution part, we use taskflow functionality and persist all
>> the details of the job.
>>
>> There we try to get the backend as below. We do upgrade everytime when a
>> job is executed.
>>
>> backend_uri = cfg.CONF.db.sqlalchemy_url
>> conf = {
>> 'connection': backend_uri,
>> }
>> self.backend = backends.fetch(conf)
>> with contextlib.closing(self.backend.get_connection()) as conn:
>> conn.upgrade()
>>
>> Now when two jobs start executing at the same time, I see below error.
>> Failed upgrading database version
>> DBAPIError: (exceptions.RuntimeError) reentrant call inside
>> <_io.BufferedReader name=14>
>>
>> We have monkey patched eventlet, is it not supposed to take care of
>> these concurrency issues?
>>
>> Below are the versions for related modules in use:
>> eventlet==0.17.4
>> taskflow==1.26.0
>> SQLAlchemy==1.0.9
>>
>> Thanks,
>> Kanthi
>>
>> On Fri, Feb 12, 2016 at 1:29 PM, Joshua Harlow <harlo...@fastmail.com
>> <mailto:harlo...@fastmail.com>> wrote:
>>
>> pn kk wrote:
>>
>> Hi Joshua,
>>
>> Yes, sure will do that once I get some window out of my work.
>>
>> One last query(hopefully :) ) , can the factory method be an
>> instance
>> method of a class?
>>
>>
>> Instance methods are particularly hard to use (since they require an
>> instance of an object to be useful); so I think the check u have hit
>> is making sure that if the flow-factory is called to recreate the
>> flow that it can do so without having import issues. Currently I
>> believe it doesn't handle instance methods (due to the complexity of
>> needing an instance attached to that method).
>>
>> Perhaps what u want is to provide a function that can be found like:
>>
>> def make_flow_factory():
>> return FlowFactory().flow_factory
>>
>> Or make flow_factory a class or static method, which should have the
>> same/similar effect.
>>
>> Hope that makes sense (more queries are fine and welcome!)
>>
>>
>> I tried giving it as "FlowFactory().flow_factory", where
>> FlowFactory is
>> my class name. It failed with below error:
>> ValueError: Flow factory <bound method FlowFactory.flow_factory of
>> <__main__.FlowFactory instance at 0x2b43b48>> is not reimportable
>> by
>> name __builtin__.instance.flow_factory
>>
>> Thanks again
>> -Kanthi
>>
>>
>> On Thu, Jan 28, 2016 at 12:29 AM, Joshua Harlow
>> <harlo...@fastmail.com <mailto:harlo...@fastmail.com>
>> <mailto:harlo...@fastmail.com <mailto:harlo...@fastmail.com>>>
>> wrote:
>>
>> pn kk wrote:
>>
>> Hi,
>>
>> Thanks for the responses. Putting it in a small example
>>
>> def flow_factory(tmp):
>> return lf.Flow('resume from backend example').add(
>> TestTask(name='first', test=tmp),
>> InterruptTask(name='boom'),
>> TestTask(name='second', test="second task"))
>>
>>
>> class TestTask(task.Task):
>> def __init__(self, name, provides=None, test,
>> **kwargs):
>> self.test=test
>> super(TestTask, self).__init__(name,
>> provides, **kwargs)
>> def execute(self, *args, **kwargs):
>> print('executing %s' % self)
>> return 'ok'
>>
>> class InterruptTask(task.Task):
>> def execute(self, *args, **kwargs):
>> # DO NOT TRY THIS AT HOME
>> engine.suspend()
>>
>> I was searching for a way in which I can reload the
>> flow after crash
>> without passing the parameter "tmp" shown above
>> Looks like "load_from_factory" gives this provision.
>>
>>
>> Thanks for the example, ya, this is one such way to do this
>> that u
>> have found, there are a few other ways, but that is the
>> main one
>> that people should be using.
>>
>>
>>
>> engine =
>>
>> taskflow.engines.load_from_factory(flow_factory=flow_factory,
>> factory_kwargs={"tmp":"test_data"}, book=book,
>> backend=backend)
>> engine.run()
>>
>> Now it suspends after running interrupt task, I can now
>> reload
>> the flow
>> from the saved factory method without passing parameter
>> again.
>> for flow_detail_2 in book:
>> engine2 =
>> taskflow.engines.load_from_detail(flow_detail_2,
>> backend=backend)
>>
>> engine2.run()
>>
>> Let me know if this is ok or is there a better approach
>> to
>> achieve this?
>>
>>
>> There are a few other ways, but this one should be the
>> currently
>> recommended one.
>>
>> An idea, do u want to maybe update (submit a review to
>> update) the
>> docs, if u didn't find this very easy to figure out so that
>> others
>> can more easily figure it out. I'm sure that would be
>> appreciated by
>> all.
>>
>>
>> -Thanks
>>
>>
>> On Wed, Jan 27, 2016 at 12:03 AM, Joshua Harlow
>> <harlo...@fastmail.com <mailto:harlo...@fastmail.com>
>> <mailto:harlo...@fastmail.com <mailto:harlo...@fastmail.com>>
>> <mailto:harlo...@fastmail.com
>> <mailto:harlo...@fastmail.com> <mailto:harlo...@fastmail.com
>> <mailto:harlo...@fastmail.com>>>>
>>
>> wrote:
>>
>> Hi there,
>>
>> Michał is correct, it should be saved.
>>
>> Do u have a small example of what u are trying to do
>> because that
>> will help determine if what u are doing will be
>> saved or
>> whether it
>> will not be.
>>
>> Or even possibly explaining what is being done
>> would be fine to
>> (more data/info for me to reason about what should
>> be
>> stored in your
>> case).
>>
>> Thanks,
>>
>> Josh
>>
>>
>> Michał Dulko wrote:
>>
>> On 01/26/2016 10:23 AM, pn kk wrote:
>>
>> Hi,
>>
>> I use taskflow for job management and now
>> trying to
>> persist
>> the state
>> of flows/tasks in mysql to recover incase of
>> process crashes.
>>
>> I could see the state and the task results
>> stored
>> in the
>> database.
>>
>> Now I am looking for some way to store the
>> input
>> parameters
>> of the tasks.
>>
>> Please share your inputs to achieve this.
>>
>> -Thanks
>>
>> I've played with that some time ago and if I
>> recall
>> correctly input
>> parameters should be available in the flow's
>> storage, which
>> means these
>> are also saved to the DB. Take a look on
>> resume_workflows method
>> on my
>> old PoC [1] (hopefully TaskFlow haven't
>> changed much
>> since then).
>>
>> [1]
>>
>> https://review.openstack.org/#/c/152200/4/cinder/scheduler/manager.py
>>
>>
>>
>>
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