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 get the result of each successfully completed Task from its property Result.

var NormalTask1 = Task.FromResult("Task result 1");
var NormalTask2 = Task.FromResult("Task result 2");
var ExceptionTk = Task.FromException(new Exception("Bad Task"));

Task[] tasks = new[] { NormalTask1, NormalTask2, ExceptionTk };
Task whenAll = Task.WhenAll(tasks);
try
{
    await whenAll;
}
catch
{
    if (whenAll.IsFaulted) // there is also the possibility of being canceled
    {
        foreach (var ex in whenAll.Exception.InnerExceptions)
        {
            Console.WriteLine(ex); // Log each exception
        }
    }
}

string[] results = tasks
    .Where(t => t.Status == TaskStatus.RanToCompletion)
    .Select(t => t.Result)
    .ToArray();
Console.WriteLine($"Results: {String.Join(", ", results)}");

Output:

System.Exception: Bad Task
Results: Task result 1, Task result 2