Ok here it is - please star it :) http://code.google.com/p/googleappengine/issues/detail?id=1797
On Jun 30, 5:31 pm, Peter Recore <peterrec...@gmail.com> wrote: > This sounds like a useful feature. If you create an issue in the > issues list I'll star it :) > > On Jun 30, 11:41 am, bFlood <bflood...@gmail.com> wrote: > > > agreed, sounds like it would be better for GAE as a whole. something > > like a simple priority value (or just low/high) when setting the cache > > would be sufficient and then GAE could figure out where to place it > > memcache > > > cheers > > brian > > > On Jun 30, 11:22 am, hawkett <hawk...@gmail.com> wrote: > > > > Thanks for the response Brian - it should be interesting to google > > > that I'm not the only one choosing not to cache data for this reason, > > > because it means that people are using more CPU and datastore > > > resources because of this issue. Given that the availability of CPU > > > (especially on a per request basis) seems to be the biggest bottleneck > > > in GAE at the moment, there may be a noticeable drop in the use of > > > this resource if developers are able to choose to use memcache more > > > effectively. Certainly I haven't heard any complaints that memcache > > > allocation is too small, so a 5% rejig as suggested would probably go > > > unnoticed. Sounds like a win-win situation. Are there any other > > > issues I'm not considering here? Thanks, > > > > Colin > > > > On Jun 30, 4:00 pm, bFlood <bflood...@gmail.com> wrote: > > > > > i agree colin, there is a lot of big data that I just don't cache in > > > > fear of evicting the smaller, more important chunks. > > > > > cheers > > > > brian > > > > > On Jun 30, 10:32 am, hawkett <hawk...@gmail.com> wrote: > > > > > > Hi, > > > > > > I'm wondering what the memcache architecture is - is it > > > > > > a) single instance with a massive pool of memory for everyone, or > > > > > b) many instances that are each shared by a few apps, or > > > > > c) an instance per app, or > > > > > d) something else? > > > > > > I'm guessing (a) if there is an intelligent LRU policy that provides > > > > > separate LRU for each app, preventing a few apps evicting everyone > > > > > else's data, or (b) if the LRU policy is not intelligent. (c) would > > > > > lead to a very poor memory utilisation. > > > > > > Apart from being interested, I am wondering about memcache > > > > > prioritisation - i.e. where the blunt LRU scheme is not suitable. I > > > > > might have a small amount of data that I really don't want evicted > > > > > from memcache (even if it is not used very often), and a large stream > > > > > of less important data for which the blunt LRU policy is fine. In the > > > > > current GAE implementation my important data can be evicted by my less > > > > > important data. > > > > > > It would be great if there was some way to prioritise memcache data - > > > > > in a stand-alone system, this would be achieved using multiple > > > > > instances, one for each priority level. > > > > > > Assuming we have option (a) with intelligent LRU on a per app basis, > > > > > then it shouldn't be too hard to provide multiple memcache instances > > > > > that can be used for prioritisation of cached data. It should be easy > > > > > enough to make this backward compatible by providing an optional > > > > > parameter to specify the instance, defaulting if it is not provided. > > > > > > I can see that this would impact memory utilisation, but it would be > > > > > possible to make the second, non-default instance much smaller than > > > > > the default one - say 5% - forcing developers to think carefully about > > > > > using the smaller cache. Even if no one uses the secondary instance, > > > > > memory utilisation can still top 95%. > > > > > > Interested to understand the issues, as this is forcing me not to > > > > > cache my 'big data' for fear of constantly evicting my 'little data'. > > > > > In my situation, my 'little data' is very important for general > > > > > response times, which are good to keep up even if the data is not used > > > > > particularly often. Essentially what I need is a cache with low > > > > > volatility, and a cache whose volatility isn't so important. Cheers, > > > > > > Colin --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
