Oh yeah, and that database lock line only works with postgresql. You might try file locking if you're not using it.
On Feb 26, 2:05 pm, Michael Toomim <[email protected]> wrote: > I got this to work by using @reboot cron. It works great, and super > simple. Cross-platform, needs no external daemons. > > The trick was that web2py wasn't shutting down when my script was > running, because I had a try-catch that was catching the > KeyboardInterrupt exception. So here's what I did: > > In cron/crontab: > > �...@reboot toomim *applications/init/cron/background_work.py > > (Thanks to achipa and massimo for fixing @reboot recently!) > In cron/background_work.py: > > import time, sys, commands, datetime > > # Lock the database so we don't accidentally run two background > # processes at the same time, e.g. if we run web2py twice by > accident > if not db.executesql('select pg_try_advisory_lock(1);')[0][0]: > logging.debug('CRON: FAILED to get background process lock') > raise Exception('Somebody else is running background > processes') > logging.debug('CRON: got lock') > > count = 0 > while True: > count += 1 > logging.debug('Sleeping for the %dth time' % count) > time.sleep(10) > try: > logging.debug('Processing launch queue') > process_launch_queue() > logging.debug('Processing bonus queue') > process_bonus_queue() > except KeyboardInterrupt as e: > logging.debug('Someone killed us.') > raise > except: > logging.debug("Error in background process: %s" % > sys.exc_info()[0]) > > Note that I explicitly catch the KeyboardInterrupt and re-raise it so > the script dies. If you kill web2py with some other type of exception > you might need to put it in there too. > > The other trick is that print statements and exceptions aren't > displayed at the console because this is run as a separate python > process. So you need to use logging.debug from log.py. I don't > remember where I got that file... > > On Jan 3, 1:57 pm, Richard <[email protected]> wrote: > > > > > I was doing that but sometimes the process crashed or was killed by my > > hosting provider, so I need a way to continue it automatically. Also I > > may want to execute a number of background tasks in parallel. And it > > uses extra resources that aren't needed, which is a problem on my > > hosting where I am reaching the limits. > > > Michael, are you looking for a particular platform solution or cross > > platform? > > > On Jan 4, 5:23 am, mdipierro <[email protected]> wrote: > > > > I normally just start a separate web2py process. > > > > python web2py.py -S app -M -S thescript > > > > On Jan 3, 11:58 am, Michael Toomim <[email protected]> wrote: > > > > > 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 thepersistent > > > > 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 <[email protected]> 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 <[email protected]> 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 <[email protected]> > > > > > > wrote: > > > > > > > > any simple example on how to create apersistentbackground 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)persistentserver-side background processes. > > > > > > > > Much thanks- Hide quoted text - > > > > > - Show quoted text - -- You received this message because you are subscribed to the Google Groups "web2py-users" group. 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