by default, will plinq use range partitioning or chunk partitioning for Dictionary<string, string>? and how to force the other?

Question

By default, will plinq use range partitioning or chunk partitioning for a Dictionary<string, string>?

This is my use case:

    Dictionary<string,string> asmachtas = new Dictionary<string,string>();
    ...
    int sum = asmachtas.AsParallel().Sum(arg => myFunction(arg));

How can I check this myself? How can I force the other type of partitioning?

Answer 1

Range partitioning only applies to collections that implement IList<>. Dictionary<,> only implements IEnumerable<> and not IList<>, so chunk partitioning would be used.

The partitioning algorithm used by PLINQ is an implementation detail, so you don't really have a way to look it up. You could put a breakpoint into the delegate passed into Sum() and deduce the partitioning scheme from the call stacks, but the stacks are rather messy.

Answer 2

As Igor said, the query would be using chunk partitioning.

I'd like to add that converting it asmachtas.ToList().AsParallel() would make it use range partitioning. Or if you were working with a list you can create a chunk-partitioner with Partitioner.Create(asmachtas, true).