Synchronizing Cache Access in ASP.NET
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Introduction
Have you ever used ASP.NET Application data caching functionality? Have you run into situations when data in the cache was inconsistent or was just not what you expected? The chances are you are running into synchronization issues when using the cache. An ASP.NET cache object has an application-wide scope and allows you to share data with several instances of the same page or multiple pages across the application. To be beneficial, the cache needs to be accessible to all the pages and to be really useful, there should be some control on who is updating the cache. If too many threads update the contents of a particular key, data will be corrupted.
ChandraMohan Lingam article on CodeGuru