How to call same method n times using tasks to run in parallel in c#?

Question

I want to call method which does time consuming job from different threads.

Public void DoSomeWork(int n)
{
  // Time Consuming operation depending on n. 
}

1 - I am trying to use task instead of thread & threadpool.
2 - There should be at max n threads running in parallel
3 - While I tried to use 'SemaphoreSlim' I found it's calling same thread calling method multiple times and run into unhanded exception.

Implementation:

 for (int i = 0; i < SomeNumberList.Count; i++)
        {
            semaphore.Wait();
            Task.Factory.StartNew(() => DoSomeWork(SomeNumberList[i])).ContinueWith(x => semaphore.Release());
        }

How to use task to call DoSomeWork by concurrent threads using task and how to do error handling for it?

Answer 1

Parallel.For already gives you the necessary marshalling for this sort of task.

    const int n = 5; // No more than "n threads"
    Parallel.For(0,  SomeNumberList.Count, new ParallelOptions{MaxDegreeOfParallelism = n}, i =>
    {
        DoSomeWork(i);
    }

There is another overload which gives you ParallelLoopState if you need to handle exceptions or break calls based on what is happening in concurrent executions.