AppFabric caching's local cache isnt working for us... What are we doing wrong?

We are using appfabric as the 2ndlevel cache for an NHibernate asp.net application comprising a customer facing website and an admin website. They are both connected to the same cache so when admin updates something, the customer facing site is updated.

It seems to be working OK - we have a CacheCLuster on a seperate server and all is well but we want to enable localcache to get better performance, however, it dosnt seem to be working.

We have enabled it like this...

  bool UseLocalCache = 
  int LocalCacheObjectCount = int.MaxValue;
  TimeSpan LocalCacheDefaultTimeout = TimeSpan.FromMinutes(3);
  DataCacheLocalCacheInvalidationPolicy LocalCacheInvalidationPolicy = DataCacheLocalCacheInvalidationPolicy.TimeoutBased;

        if (UseLocalCache)
        {
            configuration.LocalCacheProperties =
                new DataCacheLocalCacheProperties(
              开发者_运维知识库      LocalCacheObjectCount,
                    LocalCacheDefaultTimeout,
                    LocalCacheInvalidationPolicy
                    );

          //  configuration.NotificationProperties =  new DataCacheNotificationProperties(500, TimeSpan.FromSeconds(300));
        }

Initially we tried using a timeout invalidation policy (3mins) and our app felt like it was running faster. HOWEVER, we noticed that if we changed something in the admin site, it was immediatley updated in the live site. As we are using timeouts not notifications, this demonstrates that the local cache isnt being queried (or is, but is always missing).

The cache.GetType().Name returns "LocalCache" - so the factory has made a local cache.

Running "Get-Cache-Statistics MyCache" in PS on my dev environment (asp.net app running local from vs2008, cache cluster running on a seperate w2k8 machine) show a handful of Request Counts. However, on the Production environment, the Request Count increases dramaticaly.

We tried following the method here to se the cache cliebt-server traffic... http://blogs.msdn.com/b/appfabriccat/archive/2010/09/20/appfabric-cache-peeking-into-client-amp-server-wcf-communication.aspx but the log file had nothing but the initial header in it - i.e no loggin either.

I cant find anything in SO or Google.

Have we done something wrong? Have we got a screwy install of AppFabric - we installed it via WebPlatform Installer - I think? (note: the IIS box running ASp.net isnt in yhe cluster - it is just the client).

Any insights greatfully received!

Which DataCache methods are you using to read from the cache? Several of the DataCache methods will always make a hit against the server regardless of local cache being configured. You pretty much have to make sure you only use Get if you want the local cache to be leveraged.

This is one my biggest nits with AppFabric Caching. They don't explain any of this to you and so when you begin to rely on local caching you begin to fall into these little pitfalls because you do not think you're paying a penalty for talking to the service, transferring data over the wire and deserializing objects, but you are.

The worst thing is, I could understand having to talk to the service to make sure the local cache represents the latest data. I can even understand transferring the data back so that multiple calls are not made. What I can not understand for the life of me though is that even if the instance in the local cache is verified to still be the current version that came back from the cache, they still deserialize the object from the wire rather than just returning the instance that's in memory already. If your objects are large/complex this can hurt a lot.

After days and days of looking into why we get so many Local Cache misses we finally solved it:

1. There is a bug with local cache in AppFabric v 1.1 that is fixed in CU4, see http://support2.microsoft.com/kb/2800726/en-us
2. Make sure that the Microsoft.ApplicationServer.Caching.Client.dll used by your application is also updated. We had CU4 installed on the machine but got the Client.dll without CU4 from a NuGet package in our application. In our case a simple NuGet package update made everything work.

After installing CU4 and making sure that the Client.dll was also updated we reduced our reads towards the AppFabric Host by a lot, due to Local Cache hits increasing. yay!

Have you tried using a nhibernate profiler? http://nhprof.com/

There is also this: http://mdcadmintool.codeplex.com/

It's a nice way to manage and view the cache.

Both of these may help in debugging the issue.