Great! I am also trying to implement this. Richard and Auden, have
you gotten anything working yet? How about we share solutions?
My current difficulty is figuring out where to create the persistent
background thread.
- If I spawn it in a controller or model file will it be limited to
10 seconds?
- If I run it in a periodic cron there will be a delay and I will
need to handle the case of multiple threads running simultaneously
- If I use @reboot cron, it prevents web2py from shutting down (it
seems to wait for my thread to quit, which does not know to quit)
Any ideas on these problems? It would be great to have a general task
queue in web2py, like the one on GAE. Although I've never learned how
to use the GAE one, perhaps what we're making could be easier to use.
On Jan 3, 8:06 am, mdipierro <mdipie...@cs.depaul.edu> wrote:
> This is what I would do:
>
> db.define_table('queue',Field('status'),Field('descr'))
>
> In actions
>
> db.queue.insert(status='PENDING',descr='whatever')
>
> In your own scrips that you can run via CRON or via background process
>
> while True:
> tasks = db(db.queue.status=='PENDING').select(limitby=(0,10)).first
> ()
> if task:
> task.update_record(status='PROCESSING')
> db.commit()
> try:
> #process task
> task.update_record(status='COMPLETED')
> except:
> task.update_record(status='FAILED')
> db.commit()
> else:
> sleep(10) # retry in 10 seconds
>
> On Jan 3, 7:28 am, Richard <richar...@gmail.com> wrote:
>
>
>
> > I haven't implemented this yet, but my plan on Linux to keep a
> > background process running is:
>
> > - Define a task table, which is checked on every request
> > - If the task table is empty then start the background task with
> > subprocess and store the pid in the task table
> > - If the task table has an entry but its pid is not active (not in /
> > proc) then restart the background task and update the pid
> > - Else the task is running fine
>
> > Perhaps you could adapt that to your needs, assuming you are using
> > Linux.
>
> > Richard
>
> > On Dec 30 2009, 3:26 pm, Auden RovelleQuartz <oves....@gmail.com>
> > wrote:
>
> > > any simple example on how to create a persistent background process
> > > that runs continuously on the server side no matter what user signs in
> > > or out, and no matter how many concurrent users are on the system?
>
> > > Here are a couple of examples:
>
> > > when a user performs an "event", it kicks off a server side process
> > > that continues executing even when that user signs off.
>
> > > when a user performs an "event", then after a set period of time (say
> > > two days) then an email is automatically sent to a specified e-mail
> > > address that happens even if the user that triggers the event no
> > > longer has an active session on the server side.
>
> > > I am attempting to build an auction application in the web2py
> > > framework and would be interested in learning a tecqnique of starting
> > > (and stopping) persistent server-side background processes.
>
> > > Much thanks
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