How to sort a concurrent collection in .NET 4.0

Question

How to sort a concurrent collection in .NET 4.0 For example I have constructed my ConcurrentBag collection. How can I sort the elements in it?

ConcurrentBag<string> stringCollection;

ConcurrentBag<CustomType> customCollection;

Do you mean that you want a new sorted collection with all the elements at some point in time or do you want it to be sorted all the time and draw from it in that order or something to that effect? — alun, Aug 09 '11 at 04:33
I wanted to sort it using a method but there isn't any so I have to use LINQ to do the sorting. — mitul patel, Aug 09 '11 at 06:22

score 8 · Answer 1 · answered Aug 09 '11 at 04:23

8

To expand on DSW's answer, you can use the OrderBy on an enumerable.

customCollection.OrderBy(cc => cc.FieldToOrderBy);

You can also do it in descending order:

customCollection.OrderByDescending(cc => cc.FieldToOrderBy);

answered Aug 09 '11 at 04:23

evasilchenko

1,862
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can the collection be altered by another thread while it is being sorted? Or does OrderBy create a new list – Dave Lawrence Jul 23 '12 at 13:52
1

OrderBy just sorts a new IEnumerable. The underlying data structure does not change. – Berin Loritsch Apr 08 '15 at 16:24

Damith · Answer 2 · 2011-08-09T04:59:49.923

you can use OrderBy method for sorting

and also try this too..

var result = stringCollection.AsParallel().AsOrdered();

for more information check below link

http://msdn.microsoft.com/en-us/library/dd460719.aspx, you can lean how to do complex sorting using PLINQ, e.g:

 var q2 = orders.AsParallel()
       .Where(o => o.OrderDate < DateTime.Parse("07/04/1997"))
       .Select(o => o)
       .OrderBy(o => o.CustomerID) // Preserve original ordering for Take operation.
       .Take(20)
       .AsUnordered()  // Remove ordering constraint to make join faster.
       .Join(
              orderDetails.AsParallel(),
              ord => ord.OrderID,
              od => od.OrderID,
              (ord, od) =>
              new
              {
                  ID = ord.OrderID,
                  Customer = ord.CustomerID,
                  Product = od.ProductID
              }
             )
       .OrderBy(i => i.Product); // Apply new ordering to final result sequence.

But the objects remain in the concurrent collection. How can I remove the oldest items? — Kim, Oct 16 '15 at 06:06
Using the `.AsParallel()` cut my execution time over 1.7M items in half. Great tip. — dyslexicanaboko, Dec 09 '19 at 20:16

score 1 · Answer 3 · answered Aug 12 '11 at 07:30

1

you can either use PLINQ or you can write implement your own parallel sort function like the one in this article http://www.emadomara.com/2011/08/parallel-merge-sort-using-barrier.html

answered Aug 12 '11 at 07:30

Emad Omara

512
4
3

score 0 · Answer 4 · answered Aug 09 '11 at 04:22

0

Get a list from the collection, sort the list, like:

ConcurrentBag<string> bag = new ConcurrentBag<string>();

var temp = bag.ToList();
temp.Sort();//you can apply a custom sort delegate here

bag = new ConcurrentBag<string>(temp);

answered Aug 09 '11 at 04:22

Jalal Said

15,906
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1

Man, that's one expensive way to do it! – tzup Aug 09 '11 at 09:23
1

Yes I think so, I just added an alternative solution, do you think this should be deleted? – Jalal Said Aug 09 '11 at 09:24
Can't see your alternative solution even after refreshing the page. Anyway, it is up to you, but I would leave this answer as is. Don't think it will get voted down since it is not invalid. – tzup Aug 09 '11 at 09:35

How to sort a concurrent collection in .NET 4.0

4 Answers4