Yes... I've read that... The problem with using all entities as root is that I'm unable to use transactions as it is... I would have to code a lit bit... although I just found a paper describing a project that seems really good.
http://danielwilkerson.com/dist-trans-gae.html I think it will be presented this weekend, and I really hope that it goes "public" or even yet plugged to app engine! Just double-checked my GAE logs, and it seems that I'm getting timeouts in "get" operations as well... multiple requests could cause that too (one get 'over' a put for example)... Have to check my code.... Thank you On Apr 16, 2:10 pm, "Jeff S (Google)" <j...@google.com> wrote: > On Thu, Apr 16, 2009 at 4:16 AM, DarkCoiote <darkcoi...@gmail.com> wrote: > > > On Apr 15, 3:26 pm, "Jeff S (Google)" <j...@google.com> wrote: > > > Hi Ray, > > > > Which operation was is that timed out (get, query, put)? Also, how > > > consistently are you seeing these timeouts? > > > > I generally recommend catching datastore timeouts and handling them in a > > way > > > that makes sense for your app. There are currently occasional (quite rare > > as > > > a percentage) timeouts for queries and gets, and timeouts > > > > on a put is often > > > an indicator of contention on that entity or entity group. > > > well... almost (if not all) of the timeouts I'm seeing are on 'put' > > operations... > > but contention would need, like, 2 or more operations on the same > > entity > > (all my entities are roots... stupid, I know ), right? > > Actually, making most of your entities roots is often better than deep > ancestor trees in terms of overall write throughput. In a transactional > write a entity is updated which has a parent entity, the ancestors are > locked. So if nearly concurrent requests update different entities which all > share a common ancestor (in other words the entities are in the same entity > group), some of the child entity updates could fail due to contention on > writes. There are more details here in the documentation: > > http://code.google.com/appengine/docs/python/datastore/keysandentityg... > > """ > Tips for using entity groups: > > - Only use entity groups when they are needed for transactions. For other > relationships between entities, use ReferenceProperty properties and Key > values, which can be used in queries. > > - The more entity groups your application has—that is, the more root > entities there are—the more efficiently the datastore can distribute the > entity groups across datastore nodes. Better distribution improves the > performance of creating and updating data. Also, multiple users attempting > to update entities in the same entity group at the same time will cause some > users to retry their transactions, possibly causing some to fail to commit > changes. Do not put all of the application's entities under one root. > > - A good rule of thumb for entity groups is that they should be about the > size of a single user's worth of data or smaller. > > - Entity groups do not have a significant impact on the speed of queries. > """ > > If your entities are roots, then yes contention could occur if the same > entity were updated by overlapping requests. > > Thank you, > > Jeff > > > > > I'll check for bugs that could cause multiples requests and stuff like > > that.... > > > Thank you > > > > Happy coding, > > > > Jeff > > > > On Mon, Apr 13, 2009 at 4:11 PM, DarkCoiote <darkcoi...@gmail.com> > > wrote: > > > > > Looks like my and others problem... posted a few days ago: > > > > >http://groups.google.com/group/google-appengine/browse_thread/thread/. > > .. > > > > > Random datastore timeouts in totally unexpected places... > > > > > On Apr 13, 2:36 pm, Ray Malone <rayish...@gmail.com> wrote: > > > > > I'm not sure why this occurs all of a sudden. The same job runs in > > > > > 600ms. Then once in a while this runs over 6800 MS and times out. > > > > > I can't have jobs just timeout for no reason. According to my logs > > > > > during this time the only other request was a second prior. This > > > > > occurred at 04-13 09:13AM 29.627 today and other times at random in > > > > > the last few days. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to google-appengine@googlegroups.com To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~----------~----~----~----~------~----~------~--~---
