Concurrent collection with constant read time

Question

ConcurrentDictionary offer constant read time. I do not need key-value pairs, only keys.. I searched for read times on ConcurrentBag and havent found how it is implemented?

Is there a constant read time ConcurrentCollection, besides ConcurrentDictionary?

Also look at [immutable](https://learn.microsoft.com/en-us/dotnet/api/system.collections.immutable?view=netcore-3.1) collections. E.g. `ImmutableHashSet` — Alexander Petrov, Sep 26 '20 at 14:58

score 1 · Answer 1 · answered Sep 26 '20 at 08:58

ConcurrentBag is probably not what you are looking for:

Represents a thread-safe, unordered collection of objects.

Which means that it allows duplicates (whereas the dictionary doesn't)

Bags are useful for storing objects when ordering doesn't matter, and unlike sets, bags support duplicates.

As for performance, it certainly isn't as much performant as a list (so at least O(n)) (C# - Performance comparison of ConcurrentBag vs List)

For a ConcurrentSet check your luck with the custom implementation here: How to implement ConcurrentHashSet in .Net

You can also check the list of Concurrent collections to see if something else suits your needs.

Thanks. I'll go with ConcurrentCollection. – Robert Segdewick Sep 26 '20 at 09:08 — Robert Segdewick, Sep 26 '20 at 09:08
Glad I could help – Athanasios Kataras Sep 26 '20 at 10:04 — Athanasios Kataras, Sep 26 '20 at 10:04

Concurrent collection with constant read time

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