Task (System.Threading.Tasks.Task)

Table of Contents

Overview
Basic Usage
Creating Tasks
Continuations
Exception Handling
Related APIs

Overview

The Task class represents an asynchronous operation. It is the core building block of the Task Parallel Library (TPL) and provides a high‑level abstraction over threads, enabling developers to write scalable, responsive applications.

Typical scenarios include I/O‑bound work, CPU‑bound parallelism, and composing asynchronous pipelines.

Basic Usage

Running a simple asynchronous method returning a Task:

using System;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        await PerformWorkAsync();
        Console.WriteLine("Work completed.");
    }

    static async Task PerformWorkAsync()
    {
        await Task.Delay(2000); // Simulate async work
        Console.WriteLine("Async operation finished.");
    }
}

Creating and Starting Tasks

Explicit Task creation using Task.Run or the Task constructor:

Task computeTask = Task.Run(() =>
{
    // CPU‑bound work
    int result = 0;
    for (int i = 0; i < 1_000_000; i++) result += i;
    return result;
});

int sum = await computeTask;
Console.WriteLine($"Sum = {sum}");

Continuations

Chain tasks using ContinueWith or await syntax for cleaner code:

Task.Run(() => GetDataAsync())
    .ContinueWith(prev => ProcessData(prev.Result))
    .ContinueWith(_ => Console.WriteLine("All done."));
    
// Using await for the same flow
async Task Flow()
{
    var data = await GetDataAsync();
    ProcessData(data);
    Console.WriteLine("All done.");
}

Exception Handling

Exceptions are captured by the Task and re‑thrown when awaited. Use try/catch around await or inspect Task.Exception for aggregated errors.

try
{
    await Task.Run(() => { throw new InvalidOperationException("Bad thing"); });
}
catch (InvalidOperationException ex)
{
    Console.WriteLine($"Handled: {ex.Message}");
}