I'm not sure that using a cache system as a lock mechanism is a good idea. What I would do is setup a task queue (using celery and rabbitMQ) with a single worker, that way you guarantee that only one task is running at a time and you can queue as many as you want. Also, each task has a maximum lifespan, after that it kill itself and the workers starts executing the next task in the queue automatically.
On Thu, Dec 18, 2014 at 8:20 AM, Erik Cederstrand <[email protected] > wrote: > > Hi list, > > I'm using Django as a hub to synchronize data between various external > systems. To do this, I have some long-running Django management commands > that are started as cron jobs. To ensure that only one job is working on a > data set at any one time, I have implemented a locking system using the > Django cache system. > > Due to my less-than-stellar programming talent, a cron job may need to be > killed once in a while. To avoid leaving orphaned locks in the cache, I > want to clean up any locks before exiting, and I may not know which cache > keys exist at the time of exit. Therefore, I want to write a signal handler > that searches the Django cache for any entries that can be traced to the > current process (my cache keys can be used for this purpose) and delete > those. > > AFAICS, the Django cache API can't be used for this. There's cache.clear() > but I don't want to delete all cache entries. I'm using the database > backend, so I'm thinking I could access the database table directly and > issue any custom SQL on that. But it does feel hackish, so maybe one of you > have a better approach? Maybe I got the whole thing backwards? > > Here's my cache setup from settings.py: > > CACHES = { > 'default': { > 'BACKEND': 'django.core.cache.backends.db.DatabaseCache', > 'LOCATION': 'dispatch_cache', > 'TIMEOUT': None, > } > } > > > Thanks, > Erik > > -- > You received this message because you are subscribed to the Google Groups > "Django users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/django-users. > To view this discussion on the web visit > https://groups.google.com/d/msgid/django-users/9A6110DB-9D5A-4A3F-9DD3-49CC406C1C18%40cederstrand.dk > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Django users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/django-users. To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/CALn3ei0D2ZL7YJb17ibGDnBDJvTXg%2B2Hj%3DwrCZearRZBjzvpNQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
