On 25 October 2011 02:18, Kyle <kyle.rich...@gmail.com> wrote: > Is there a reason that you didn't use the memcached service to > implement semaphores? > > -Kyle
I'm assuming you mean Memcache? Well, two things. Firstly, as far as I know there are no transactions or locks or anything like that for memcache, so where you need a critical section, how will you implement it? (This is not actually a rhetorical question; is there a way?) Secondly, you can't trust Memcache to stick around, as far as I know. If one task constructs a semaphore in memcache, then will that still be there when another tasks tries to wait() on it? Anything that is implemented in terms of Semaphores really needs to be able to rely on them to behave. It might be good to come up with an alternative construct that can tolerate memcache's behaviour, I'm totally open to suggestions. > > On Oct 23, 6:23 am, Emlyn <emlynore...@gmail.com> wrote: >> Here's a new AppEngine article from me, "The Dining Philosophers". It >> includes a full working implementation of Semaphores using the >> Datastore, and implementation of flawed and successful solutions to >> the classic Dining Philosophers problem using Semaphores. >> >> http://appenginedevelopment.blogspot.com/2011/10/dining-philosophers.... >> >> Fun for hard core comp sci types ;-) >> >> -- >> Emlyn >> >> http://my.syyn.cc- Synchonise Google+, Facebook, WordPress and Google >> Buzz posts, >> comments and all.http://point7.wordpress.com- My blog >> Find me on Facebook and Buzz > > -- > 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. > > -- Emlyn http://my.syyn.cc - Synchonise Google+, Facebook, WordPress and Google Buzz posts, comments and all. http://point7.wordpress.com - My blog Find me on Facebook and Buzz -- 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.
