Hi, On Google App Engine servers, to prevent wasted work, items are not evicted from memcache's memory until there is memory pressure (it shouldn't return expired results, but the item still might be in the cache, as it seems to be the case here). This is what oldest_item_age measures:
oldest_item_age: How long in seconds since the oldest item in the cache was accessed. Effectively, this indicates how long a new item will survive in the cache without being accessed. This is _not_ the amount of time that has elapsed since the item was created. Which is different from expiration time for an item. This stat is mostly useful when oldest_item_age is less than your highest expiration, telling you that you are under memory pressure. The dev_appserver's memcache implementation inevitably differs under the covers, so the stats there are not as useful, hence the difference in the measurements. -Marzia On Thu, Jan 15, 2009 at 9:27 AM, Marzia Niccolai <[email protected]> wrote: > Hi, > > A cache miss is when you make a get() call for a key, and the object > is not in the cache, either because it is expired or has been ejected. > > I'm not aware of any current issues that would cause memcache items to > stick around after they have expired, so would you mind providing some > information? The code used to set and retrieve the key with which you > have noticed this would be helpful, the key name, and also, the app > id. > > -Marzia > > On Wed, Jan 14, 2009 at 8:02 PM, ten_foot_ninja <[email protected]> wrote: >> >> The docs say: >> misses: Number of cache get requests resulting in a cache miss. >> What is a "cache miss" exactly? >> >> As well, I set an expiration time to 3600 and get_stats reports the >> oldest accessed item is 19477 seconds old. The exact same code on my >> dev server worked as expected. >> >> >> >> > --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
