什么是最快的基于字典的类实现？

Question

Which one of the C# <Key, Value> structure implementations has better performance and higher speed?

PS1: I Have two thread, one of them writes into collection, and another one reads and writes into it.

PS2: Key items are random numbers, and then my access is random. Write and read actions are simultaneous. I am using hashtable, but I want to know is there any better implementation with less resource usage and better performance?

Answer 1

For profiling yourself, there are many options. One free profiler I've used and which I would recommend is EQATEC . There are plenty more to choose from, many of which are referenced in this SO question .

As for implementations, the first few that pop into mind are Dictionary<TKey, TValue> , SortedDictionary<TKey, TValue> and SortedList<TKey, TValue> . Of course, I would be inclined to guess that Dictionary<TKey, TValue> is the fastest since it's the simplest in terms of features. But I haven't ever tested them against one another for speed.

Note that the above classes are all generic, which should make them more efficient than HashTable in at least one sense: they do not require boxing/unboxing of keys and values as System.Object , which results in unnecessary memory allocation.

Something else to be aware of is that since you're in a multithreaded scenario, you'll need to take care to lock your reads/writes somehow. (The above classes, unlike HashTable , are not guaranteed to be thread-safe for multiple readers and a writer.) Locking on a common object may be your best bet in most cases, whereas if you're performing more reads than writes you might want to consider using a ReaderWriterLock or ReaderWriterLockSlim (both of which permit switching between multiple simultaneous readers and a single writer). If you are enumerating over the collection then you should really be locking anyway--even with a HashTable .