C# Task Parallel Library

The Task Parallel Library (TPL) provides high-level tools for parallelism and concurrency beyond simple async/await.

1 - Parallel.For and Parallel.ForEach

// CPU-bound parallel work
Parallel.For(0, 10, i =>
{
    Console.WriteLine($"Processing item {i} on thread {Thread.CurrentThread.ManagedThreadId}");
});

var files = Directory.GetFiles("images", "*.png");
Parallel.ForEach(files, file =>
{
    // Resize each image in parallel
    ProcessImage(file);
});

2 - Task.Run for CPU-bound Work

public static async Task<int> HeavyComputationAsync(int input)
{
    // Offload CPU work to a thread pool thread
    return await Task.Run(() =>
    {
        int result = 0;
        for (int i = 0; i < input; i++) result += i;
        return result;
    });
}

int sum = await HeavyComputationAsync(1_000_000);
Console.WriteLine(sum);

3 - async Streams (C# 8+)

public static async IAsyncEnumerable<int> GenerateAsync()
{
    for (int i = 0; i < 10; i++)
    {
        await Task.Delay(100); // simulate async source
        yield return i;
    }
}

await foreach (int value in GenerateAsync())
    Console.WriteLine(value);