Ignore the Tasks throwing Exceptions at Task.WhenAll and get only the completed results

Question

I am working on a Task parallel problem that I have many Tasks that may or may not throw Exception.

I want to process all the tasks that finishes properly and log the re

Answer 1

You can create a method like this to use instead of Task.WhenAll:

public Task[]> WhenAllOrException(IEnumerable> tasks)
{    
    return Task.WhenAll(
        tasks.Select(
            task => task.ContinueWith(
                t => t.IsFaulted
                    ? new ResultOrException(t.Exception)
                    : new ResultOrException(t.Result))));
}


public class ResultOrException
{
    public ResultOrException(T result)
    {
        IsSuccess = true;
        Result = result;
    }

    public ResultOrException(Exception ex)
    {
        IsSuccess = false;
        Exception = ex;
    }

    public bool IsSuccess { get; }
    public T Result { get; }
    public Exception Exception { get; }
}

Then you can check each result to see if it was successful or not.

---

EDIT: the code above doesn't handle cancellation; here's an alternative implementation:

public Task[]> WhenAllOrException(IEnumerable> tasks)
{    
    return Task.WhenAll(tasks.Select(task => WrapResultOrException(task)));
}

private async Task> WrapResultOrException(Task task)
{
    try
    {           
        var result = await task;
        return new ResultOrException(result);
    }
    catch (Exception ex)
    {
        return new ResultOrException(ex);
    }
}