This still has a big problem. It only checks status when starting the loop. If thread 2 starts, and then thread 1 does a row, thread 2 will do that row too.
On Dec 28, 11:19 pm, Thadeus Burgess <thade...@thadeusb.com> wrote: > for db(status == 'pending').select(): > task.update_record(status == 'processing') > success = do_long_thing_with(task) > fail > if success: > task.update_record(status = 'done') > > This way, records that have a status of processing will not get pulled > in by a concurrent thread. > > -Thadeus > > > > On Tue, Dec 29, 2009 at 1:07 AM, toomim <too...@gmail.com> wrote: > > What's the best way to use web2py to process a queue of data in a cron > > job without race conditions? > > > My code basically does this: > > > for task in db(status != 'done').select(): > > success = do_long_thing_with(task) # takes a long time, might > > fail > > if success: > > task.update_record(status = 'done') > > > I launch this every N minutes in a cron job. But if it takes more > > than N minutes to run, the cron starts another loop in parallel and > > duplicates all calls to do_long_thing_with(task). > > > What's the best way to fix this? It seems hard without being able to > > manually say where transactions should start with BEGIN. > > > -- > > > You received this message because you are subscribed to the Google Groups > > "web2py-users" group. > > To post to this group, send email to web...@googlegroups.com. > > To unsubscribe from this group, send email to > > web2py+unsubscr...@googlegroups.com. > > For more options, visit this group > > athttp://groups.google.com/group/web2py?hl=en. -- You received this message because you are subscribed to the Google Groups "web2py-users" group. To post to this group, send email to web...@googlegroups.com. To unsubscribe from this group, send email to web2py+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/web2py?hl=en.
