Azure appfabric cache as provider for distributed outputcache in multiple webroles fires errors "Failed to start monitoring file changes"

Question

Crystal clear :

Step 1

• Create a webrole with a few websites with a default.aspx file and a plain regular <%@ OutputCache Duration="3600" VaryByParam="*" %>, in the webconfig use the appfabric cache provider for outputcache and link to your cache subscription in azure with provided code

• Use only one instance of the webrole, lauch the page, it chaches it, reload few times, it works solid

Step 2

• Now increase to 2 or more instances of this WebRole

• Here is my problem, reload your default.aspx page on client, now depending of the Webrole the loadbalancer will direct your request, you might get a System.Web.Caching.CacheDependency error upon the fact that the default.aspx cached in distributed cache seems to be based on a file monitoring dependancy, a hard path of the default.aspx page like "E:\sitesroot\2\". But you may have (and you do) "F:\sitesroot\2\" on the other instances of the Webrole.

So it fires an error :

System.Web.HttpException (0x80070003): Directory 'E:\sitesroot\2' does not exist. Failed to start monitoring file changes.

  at System.Web.FileChangesMonitor.FindDirectoryMonitor(String dir, Boolean addIfNotFound, Boolean throwOnError)
  at System.Web.FileChangesMonitor.StartMonitoringPath(String alias, FileChangeEventHandler callback, FileAttributesData& fad)
  at System.Web.Caching.CacheDependency.Init(Boolean isPublic, String[] filenamesArg, String[] cachekeysArg, CacheDependency dependency, DateTime utcStart)
  at System.Web.Caching.CacheDependency..ctor(Int32 dummy, String[] filenames)
  at System.Web.Caching.OutputCache.HasDependencyChanged(Boolean isFragment, String depKey, String[] fileDeps, String kernelKey, String oceKey, String providerName)
  at System.Web.Caching.OutputCache.Get(String key)
  at System.Web.Caching.OutputCacheModule.OnEnter(Object source, EventArgs eventArgs)
  at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
  at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

I'm struggling with this errors since one week, i don't get it, if anyone knows a way for implementing distributed outputcache over multiple instances of webroles please share your solution.

EDIT

I ended dropping completely asp.net outputcache provider for appfabric and writing a custom cache with appfabric. Works great, few line of codes and cachedependancy on azure made easy.

Answer 1

I ended dropping completely asp.net outputcache provider for appfabric and writing a custom cache with appfabric. Works great, few line of codes and cachedependancy on azure made easy.