Parallel for each confusion C#

[zappian]

So I want to iterate trought a dicitonary using a parallel for each.

Which is the source collection and which is the item ?

My code is like this:

List <int> procura(Dictionary <int, string> dicionario, string padrao){	List <int> rout = new List<int>;	Parallel.ForEach(dicionario, d=> 	{		bool result  = Task.Factory.StartNew(() =>contem(d.Item2,padrao);		if(result == true)		{			rout.add(d.Item1);		}	});	return rout;}

I am using this as reference:

https://msdn.microsoft.com/en-us/library/dd537608.aspx

[madknight3]

Which is the source collection and which is the item ?

 

The source collection is dicionario and the item is d

[DevBlox]

You're likely to have high contention rate (many attempts from threads trying to get locks). Try using ConcurrentDictionary instead.