DD4T 2 Ehcache settings: DD4T-Objects vs DD4T-Dependencies

Question

The ehcache.xml file expects settings defined for "DD4T-Objects" and "DD4T-Dependencies". In a typical implementation what percentage volume of items might we expect to be in the DD4T-Objects cache versus the DD4T-Dependencies cache? Alternatively, how can I calculate this for my specific implementation?

Knowing this information will help me to determine what to specify in the "maxEntriesLocalHeap" for both "DD4T-Objects" and "DD4T-Dependencies", so any additional information on setting the "maxEntriesLocalHeap" values would be greatly appreciated.

Answer 1

As far as I understand the EHCache implementation in DD4T 2, it is quite simplistic. It maps request URLs to the Tridion item it depends on. Items are entered into the EHCache with only that dependency. See EHCacheProvider.java

For example cache item '9-/ww/en/index.jsp' would have a dependent item key of '9:1234' - publication id 9, page id 1234

To see what the dependency key is for each item type you can look at the associated factory (e.g for Page PageFactoryImpl) for details

You can always create an admin page to review your cache, to get an idea of it's structure

Answer 2

Did you finally get some conclusions? The EHCache is detected as a leak in our heapdump because it's arriving to get 1Gb of it. I guess EHCache is not at all a good implementation for large/intensive systems were an external cache is more useful, we are considering to disable the DD4T cache but we don't know yet how this could affect the performance & throughput of our application