Why isn't Parallel.ForEach running multiple threads?

Question

Today i tried do some optimization to foreach statement, that works on XDocument.

Before optimization:

foreach (XElement el         


        

Answer 1

Do you happen to have a single processor? TPL may limit the number of threads to one in this case. Same thing may happen if the collection is very small. Try a bigger collection. See this answer for more details on how the degree of parallelism is determined.