Mastering Task Parallel Library (TPL) Methods in C#: A Comprehensive Guide

The Task Parallel Library (TPL) in C# is a powerful framework for managing and executing parallel tasks efficiently. It simplifies the development of multi-threaded and concurrent applications. In this article, we'll explore the core TPL methods and provide real-world examples for each one.

Task.Run(Action action)

Task.Run is a simple way to run a specified action asynchronously on a separate thread.

Example:

Task task = Task.Run(() => Console.WriteLine("Task is running..."));
task.Wait();

Task.Factory.StartNew(Action action)

Task.Factory.StartNew is similar to Task.Run and allows you to run an action asynchronously.

Example:

Task task = Task.Factory.StartNew(() => Console.WriteLine("Task is running..."));
task.Wait(); 

Task.Delay(int milliseconds)

Task.Delay creates a task that delays execution asynchronously for the specified time.

Example:

async Task DelayExample()
{
    Console.WriteLine("Start of DelayExample");
    await Task.Delay(2000); // Delay for 2 seconds
    Console.WriteLine("After 2 seconds delay");
}

Task.WhenAll(IEnumerable<Task> tasks)

Task.WhenAll waits for all the provided tasks to complete.

Example:

async Task WhenAllExample()
{
    var tasks = new List<Task>
    {
        Task.Run(() => Console.WriteLine("Task 1")),
        Task.Run(() => Console.WriteLine("Task 2")),
        Task.Run(() => Console.WriteLine("Task 3"))
    };

    await Task.WhenAll(tasks);
    Console.WriteLine("All tasks completed.");
}

Task.WhenAny(IEnumerable<Task> tasks)

Task.WhenAny returns the task that completes first.

Example:

async Task WhenAnyExample()
{
    var tasks = new List<Task>
    {
        Task.Delay(2000).ContinueWith(_ => 1),
        Task.Delay(1000).ContinueWith(_ => 2),
        Task.Delay(3000).ContinueWith(_ => 3)
    };

    var firstCompletedTask = await Task.WhenAny(tasks);
    Console.WriteLine("First task completed with result: " + await firstCompletedTask);
}

Parallel.ForEach(IEnumerable<TSource> source, Action<TSource> body)

Parallel.ForEach enables parallel processing of a collection.

Example:

var numbers = Enumerable.Range(1, 10);
Parallel.ForEach(numbers, num =>
{
    Console.WriteLine($"Processed number {num}");
});

Parallel LINQ (PLINQ)

PLINQ allows parallel processing of data collections using LINQ queries.

Example:

var numbers = Enumerable.Range(1, 1000);
var parallelQuery = numbers.AsParallel().Where(num => num % 2 == 0);
foreach (var num in parallelQuery)
{
    Console.WriteLine($"Even number: {num}");
}