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.NET - Multi-threaded iteration over one list (Of T). What do I need to watch out for?

I am using VB.NET.

I want to create a large list (MyClassOrStructure) that will become static after its initial collection.

I will have multiple threads that need to iterate through this list to read data (no write, insert, or delete)

Are there any really bad things that I should watch out for?

Thank.

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3 answers


If you're just reading, that's okay. Each iterator will be independent of the others.



If you've ever wondered why an interface IEnumerable<T>

doesn't have a direct MoveNext()

and Current

, but instead must instantiate IEnumerator<T>

, so - the list itself doesn't store the "cursor" says where the iterator is at IEnumerator<T>

. Sharing values IEnumerator<T>

between threads is almost certainly a bad idea, but you are unlikely to do it by accident. The natural way to iterate over multiple threads would be to have one IEnumerator<T>

for each thread, which is safe (as long as you don't modify the list).

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If the values ​​are static I don't see the need to lock, but if it ever happened that you rarely write to an object, you can look at the ReaderWriterLock class



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you clearly need some kind of locking if both read and write are involved. the best approach is to use read / write locks. see ReaderWriterLockSlim .

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