Concurrency in C# Cookbook

IProgress and Progress types

new CancellationTokenSource(TimeSpan.FromSeconds(3));

For more information on System.Reactive, I recommend the excellent online book Introduction to Rx.

Tasks should neither be extremely short, nor extremely long.
If your tasks are too short, then the overhead of breaking up the data into tasks and scheduling those tasks on the thread pool becomes significant. If your tasks are too long, then the thread pool cannot dynamically adjust its work balancing efficiently. It’s difficult to determine how short is too short and how long is too long; it really depends on the problem being solved and the approximate capabilities of the hardware

in general, parallel programming on the server would work against its built-in parallelism and therefore wouldn’t provide any real benefit