Calling transaction.commit() after object.save results in a TransactionManagementError. I mentioned at the end that I am using MySQL (5.5.27). The issue is not that the Gearman workers are having trouble saving their transactions, it's that they are having trouble looking up the incoming object. I'm assuming the view and workers are separate transactions since I don't see how they could be connected -- though I'm looking into this.
On Tuesday, May 21, 2013 1:05:54 PM UTC-4, Tom Evans wrote: > > On Tue, May 21, 2013 at 4:23 PM, Chris Conover > <clc...@gmail.com<javascript:>> > wrote: > > Hello, > > > > I'm having an issue looking up objects immediately after they are saved > and > > am wondering if anyone has any advice on how to address the problem. > > Specifically, I'm saving an object in a view (nothing fancy, a simple > > save()) and then kicking off a Gearman task to do some operations on > that > > saved object in the background. I pass the newly created object's PK as > data > > to the Gearman worker which then does a simple > Objects.objects.get(pk=PK). > > However, almost all of the time this lookup operation fails with an > > DoesNotExist exception. I believe the problem has to do with > transactions. > > Namely, the read in the Gearman worker is happening before the write > from > > the view is committed to the database. I've tried several things > including > > refactoring the saving code to be wrapped in a > > @transaction.commit_on_success block, moving the worker submission to > > post_save and adding a long delay before the Gearman worker does the > lookup. > > Nothing really seems to solve the problem completely. Even with a 60 > second > > delay, the lookup fails with some frequency. Am I missing something > here? Is > > there some Django query cache that I can clear? Or should I just rewrite > all > > this to just to use a look-back perspective. > > > > The stack is Django 1.4 connecting to MySQL 5.5.27. Django is handling > > 200-1000 requests per second and the database is handling about double > that. > > > > Thanks, > > Chris > > from django import transaction > … > obj.save() > transaction.commit() > task.submit(obj.id) > > You will also need to make sure that gearman is doing things correctly > as well. You haven't mentioned what database you are using, but if > gearman's DB connection is in a read repeated mode, you can do > whatever you like in django but you won't see new data in gearman > until gearman's current transaction is committed. > > Cheers > > Tom > -- 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 django-users+unsubscr...@googlegroups.com. To post to this group, send email to django-users@googlegroups.com. Visit this group at http://groups.google.com/group/django-users?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
