One more thing to be aware of: there are times when Memcache needs to be flushed. If a flush happens sometime, B can have a value, but A would be unset.
Ikai Lan Developer Programs Engineer, Google App Engine Blog: http://googleappengine.blogspot.com Twitter: http://twitter.com/app_engine Reddit: http://www.reddit.com/r/appengine On Fri, Jul 22, 2011 at 1:53 PM, Ikai Lan (Google) <ika...@google.com>wrote: > Oh, I see what you're getting at: you're asking me if B will still be in > the cache if A is still in the cache. That depends on whether or not the > keys hash to the same Memcache instance. > > FYI - in general, we don't make any guarantees of this behavior, so it > potentially can be problematic down the line if this changes. > > > Ikai Lan > Developer Programs Engineer, Google App Engine > Blog: http://googleappengine.blogspot.com > Twitter: http://twitter.com/app_engine > Reddit: http://www.reddit.com/r/appengine > > > > On Fri, Jul 22, 2011 at 1:52 PM, Ikai Lan (Google) <ika...@google.com>wrote: > >> Memcache works like an LRU cache, but I don't see why a would force out b >> unless you ran out of space. >> >> Also, App Engine's Memcache has 2 LRU structures: an app specific LRU and >> a global LRU for that Memcache instance. >> >> Ikai Lan >> Developer Programs Engineer, Google App Engine >> Blog: http://googleappengine.blogspot.com >> Twitter: http://twitter.com/app_engine >> Reddit: http://www.reddit.com/r/appengine >> >> >> >> On Fri, Jul 22, 2011 at 1:05 PM, Andrin von Rechenberg < >> andri...@gmail.com> wrote: >> >>> Hey there >>> >>> I'm building something like "Google Analytics" for Appengine but in real >>> time >>> (Including qps, hourly & daily graphs, backend counters, monitors with >>> alerts, etc...) >>> The cool thing is that it only uses memcache to increase counters/stats >>> so its >>> really quick to use in prod code. Every minute I gather all counters and >>> write them to datastore. >>> It seems to work perfectly for my app (~250qps with about 1000 different >>> counters, and about >>> 1000 counter increases per second) >>> I can also measure how correct my data is (if stuff flushed in memcache, >>> but so far that never happened), >>> but it's all based on one assumption: >>> >>> If I call: >>> >>> memcache.incr("a", intitail_value=0) >>> ... >>> memcache.incr("b", initial_value=0) >>> .... >>> memcache.incr("b", initial_value=0) >>> .... >>> >>> *if "a" is still in the memcache "b" will also be in the memcache and >>> wont have been flushed, correct?* >>> * >>> * >>> or in other words: If the entity size for two items in the memcache is >>> the same, >>> does the memcache work like either a LRU or FIFO cache? >>> >>> Any response is greatly appreciated... >>> >>> -Andrin >>> >>> -- >>> 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. >>> >> >> > -- 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.
