Hello John, Thank you for your message. I was looking at your project and indeed it does pretty much what I was looking for.
I think memcache is good for basic caching problems but it could be made more efficient if it would keep most used data on the local machine memory to cut the costs for the network overhead. The problem is that from application side our local data gets lost when the application is cycled out. Google could provide a solution that survives this time-out and that uses resources more efficiently. Other discussions about ehcache show that there is a need for something more sophisticated. Maybe something for the roadmap? Cheers, Toby On Jun 18, 10:33 am, John Patterson <jdpatter...@gmail.com> wrote: > Hi Toby, > > I made some code public that does what you describe: it is a simple > cache interface that has implementations for in-memory,memcacheand > the datastore. You get about 100MB of heap space to use which can > significantly speed up your caching. > > There is also a CompositeCache class that allows you to layer the > caches so that it first checks in-memory, thenmemcache, then the > datastore. Puts go to all levels and cache hits refresh the higher > levels. e.g. if an item is not in-memory and has been flushed from > memcachebut is still present in the datastore then the other two will > be updated. > > http://code.google.com/p/stick-cache/ > > Hope this helps, > > John > > On 18 Jun 2010, at 15:08, Toby wrote: > > > Hello Ikai, > > > Sorry but I might have worded my post incorrectly. I do not doubt > >memcache, in fact I use it very heavily and it is great. > > > On Google I/O I learned thatmemcacheis actually hosted on another > > machine and that for each request a significant network overhead is > > involved. In appstats I see about 20ms for a single request. Simple > > data-store requests are also between 20-50ms. So in factmemcacheis > > good as second level cache but shows to be a bottleneck for data that > > I heavily use over and over again (plus it costs valuable API time). > > > So the idea was to have some "first level" in-memory cache living on > > the same machine that is holding heavily used data to prevent the > > server round trip to the cache machine. Now you might tell me that my > > application is designed wrong. And indeed I could just put this in by > > myself. But as you also pointed out there are tricky parts like memory > > boundaries and other things to take care of. This is why I started > > this thread to see if someone has come up with a good solution. > > > I think multiple cache layers are kind of a standard approach that has > > shown its usefulness in many places. It would be good to have that as > > part of GAE. Of course this is not the most urgent issue. > > > Cheers, > > Toby > > > On Jun 17, 6:46 pm, "Ikai L (Google)" <ika...@google.com> wrote: > >> What aspect ofMemcacheis too slow? Have you run AppStats yet? > > >> The overhead ofMemcacheis low enough for many of the top sites on > >> the > >> internet to use. Some sites are listed on the main page here: > > >>http://memcached.org/ > > >> As you move closer and closer to local memory, the volatility of > >> your cache > >> will increase, so the only items I would store in local memory are > >> items > >> that are okay to lose. If you want, you can probably layer your > >> application > >> to fetch frommemcache-> fetch from authoritative source and place > >> into > >> local memory on a cache miss. Just be aware that there are process > >> memory > >> limits, and exceeding these will force a restart. > > >> On Thu, Jun 17, 2010 at 2:30 AM, Toby <toby.ro...@gmail.com> wrote: > >>> Hello, > > >>> I wonder if there is a framework (such as Objectify) also for > >>>memcache. Asmemcacheis not on the local machine it is rather > >>> slow, > >>> especially for reoccurring requests. So on Google I/O they suggested > >>> to build your own in-memory layer around that. I know that is an > >>> easy > >>> task, still I wonder if there might already be a framework for > >>> that :-) > > >>> Also I wonder if someone can give me some ideas about how to build > >>> an > >>> in-memory cache. I guess it is just a static hashmap. But will it > >>> survive multiple requests? How much can I put in there? > > >>> As the problem ofmemcacheis apparently the high latency for the > >>> network traffic to the server I had the idea to store the in-memory > >>> cache in thememcache, de-serialize it and then use it? > > >>> Do you have other ideas how to speed up caching? > > >>> Thank you for your advice, > > >>> Toby > > >>> -- > >>> You received this message because you are subscribed to the Google > >>> Groups > >>> "Google App Engine for Java" group. > >>> To post to this group, send email to > >>> google-appengine-j...@googlegroups.com. > >>> To unsubscribe from this group, send email to > >>> google-appengine-java+unsubscr...@googlegroups.com<google-appengine-java%2bunsubscr...@googlegroups.com > > >>> . > >>> For more options, visit this group at > >>>http://groups.google.com/group/google-appengine-java?hl=en. > > >> -- > >> 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 > > > -- > > You received this message because you are subscribed to the Google > > Groups "Google App Engine for Java" group. > > To post to this group, send email to google-appengine-java@googlegroups.com > > . > > To unsubscribe from this group, send email to > > google-appengine-java+unsubscr...@googlegroups.com > > . > > For more options, visit this group > > athttp://groups.google.com/group/google-appengine-java?hl=en > > . -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. 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