I'm pretty sure the data consistency is not in our application because of the characteristics of the problem. I do not use Memcache or a per- instance in-memory cache, and perform direct reads from the datastore as the application is high-write, low-read.
I can reproduce this problem at will by just refreshing a page that reloads the data from the datastore. About 20% of the time I get an incorrect value. The data is being written using a cron that fires every 10 minutes, and there are no other writers to this entry. Thus I'm pretty sure that it's not being performed by an incorrect write. >From the characteristics, it seems to me like there's an instance serving the application that is stale and serving bad data. Perhaps this instance is in a different datacenter than the main set of instances, and thus Megastore replication has fallen behind, or is in an inconsistent state? I've been working with AppEngine for nearly the last year, and haven't seen this bizarre behavior before. Is there a way to escalate such issues for someone in Google to have a look? Thanks! On Nov 19, 8:31 am, Robert Kluin <[email protected]> wrote: > I did not see anything quite like that. It sort of sounds like you > might have a cache bug. Perhaps instance variables are being used as > cache? > > Robert > > > > > > > > On Fri, Nov 19, 2010 at 04:04, Sanjay <[email protected]> wrote: > > Hello, > > > Starting earlier today around the time of the App Engine deploy > > outage, I'm seeing a lot of data inconsistency. Data written several > > minutes earlier cannot be read back consistently. Even more > > surprisingly, just retrying the operation multiple times yields older > > versions of the same data. Is anyone else seeing this? > > > Thanks, > > Sanjay > > > -- > > You received this message because you are subscribed to the Google Groups > > "Google App Engine" group. > > To post to this group, send email to [email protected]. > > To unsubscribe from this group, send email to > > [email protected]. > > For more options, visit this group > > athttp://groups.google.com/group/google-appengine?hl=en. -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.
