Have a set of Tasks with only X running at a time

Question

Let's say I have 100 tasks that do something that takes 10 seconds. Now I want to only run 10 at a time like when 1 of those 10 finishes another task gets executed till all are finished.

Now I always used ThreadPool.QueueUserWorkItem() for such task but I've read that it is bad practice to do so and that I should use Tasks instead.

My problem is that I nowhere found a good example for my scenario so could you get me started on how to achieve this goal with Tasks?

Answer 1

SemaphoreSlim maxThread = new SemaphoreSlim(10);  for (int i = 0; i < 115; i++) {     maxThread.Wait();     Task.Factory.StartNew(() =>         {             //Your Works         }         , TaskCreationOptions.LongRunning)     .ContinueWith( (task) => maxThread.Release() ); } 

Answer 2

TPL Dataflow is great for doing things like this. You can create a 100% async version of Parallel.Invoke pretty easily:

async Task ProcessTenAtOnce<T>(IEnumerable<T> items, Func<T, Task> func) {     ExecutionDataflowBlockOptions edfbo = new ExecutionDataflowBlockOptions     {          MaxDegreeOfParallelism = 10     };      ActionBlock<T> ab = new ActionBlock<T>(func, edfbo);      foreach (T item in items)     {          await ab.SendAsync(item);     }      ab.Complete();     await ab.Completion; }