July 6, 2007
Collection Performance Comparisons
This is not part of my series on performance tuning a specific app.
Problem: I have a Registry class in which I want to place a generic collection of objects. In this way I can add new items to the registry on the fly (i.e. from a user application), without having to recompile the library containing the the class. What is my best option, in terms of performance, for a .Net 2.0 collection to hold my mixed-bag of objects? I'll be referring to these with a string name.
Solution: I was contemplating both a Hashtable and a HybridDictionary. Rather than testing the relative performance myself, I got lazy. And lucky, as Performance Quiz #4 -- Of Sets and Sundry is a great find. In my case I'm not expecting to have many objects in the collection, but you never know. Therefore HybridDictionary is the way to go (based on the linked analysis).
But the more I think about it, what I really want is a collection that takes a string for the key (to avoid boxing) and a weakly-typed object as the value. Is there a better option that I'm forgetting about? Perhaps I should try implementing a NameObjectCollectionBase, leaving the object part as, well, an object. But that's not going to be helpful either, because under the hood it would still be using a DictionaryEntry, whose constructor not surprisingly takes two objects.
So for now I'll go with the HybridDictionary. Perhaps I could write my own collection class that would get the job done; maybe I could do some more research and find that Microsoft has already provided the answer for me. But that's just not worth the return on investment at this point.