await Task.Factory.StartNew(() => versus Task.Start; await Task;

Question

Is there any functional difference between these two forms of using await?

1. string x = await Task.Factory.StartNew(() => GetAnimal("feline")); 

2. Task<string> myTask = new Task<string>(() => GetAnimal("feline")); myTask.Start(); string z = await myTask; 

Specifically, in what order is each operation called in 1.? Is StartNew called and then is await called, or is await called first in 1.?

Answer 1

When you're writing code with async and await, you should use Task.Run whenever possible.

The Task constructor (and Task.Start) are holdovers from the Task Parallel Library, used to create tasks that have not yet been started. The Task constructor and Task.Start should not be used in async code.

Similarly, TaskFactory.StartNew is an older method that does not use the best defaults for async tasks and does not understand async lambdas. It can be useful in a few situations, but the vast majority of the time Task.Run is better for async code.