Task.Run vs. TaskFactory.StartNew

When working with asynchronous or parallel code in C#, you’ll inevitably encounter two common ways to start tasks: Task.Run and TaskFactory.StartNew. At first glance, they seem similar - but they behave differently and should be used appropriately depending on the context.

In this article, you’ll learn:

• What the difference is between Task.Run and TaskFactory.StartNew
• Which one you should prefer
• Code examples for both approaches

Task.Run

Task.Run was introduced in .NET 4.5 to simplify asynchronous programming. It wraps the more complex TaskFactory.StartNew with sensible defaults and is ideal for offloading CPU-bound work.

Example

1public Task RunWithTaskRunAsync()
2{
3    return Task.Run(() =>
4    {
5        // Simulated background work
6        Thread.Sleep(1000);
7        Console.WriteLine("Executed with Task.Run");
8    });
9}

Key Characteristics

• Uses TaskScheduler.Default (ThreadPool)
• Ideal for CPU-bound operations
• Automatically flows the current execution context (e.g., HttpContext, SecurityContext)
• Simple to use

TaskFactory.StartNew

TaskFactory.StartNew offers full control over task creation. You can configure schedulers, creation and continuation options - at the cost of increased complexity.

Simple Example

 1public Task RunWithTaskFactoryAsync()
 2{
 3    TaskFactory factory = new TaskFactory();
 4
 5    return factory.StartNew(() =>
 6    {
 7        Thread.Sleep(1000);
 8        Console.WriteLine("Executed with TaskFactory.StartNew");
 9    });
10}

With Configuration Options

 1public Task RunWithTaskFactoryOptionsAsync()
 2{
 3    TaskFactory factory = new TaskFactory(
 4        CancellationToken.None,
 5        TaskCreationOptions.DenyChildAttach,
 6        TaskContinuationOptions.None,
 7        TaskScheduler.Default);
 8
 9    return factory.StartNew(() =>
10    {
11        Thread.Sleep(1000);
12        Console.WriteLine("Executed with TaskFactory and options");
13    });
14}

Comparison Table

🟢 Recommendation

• ✔ Use Task.Run for offloading simple CPU-bound tasks in async code.
• ❌ Avoid TaskFactory.StartNew unless you need custom configuration, scheduling, or advanced scenarios.
• ⚠️ Do not use TaskFactory.StartNew with async lambdas, unless you’re explicitly handling the returned Task - it does not unwrap the async method properly.

Conclusion

In modern .NET applications, Task.Run is almost always the safer and cleaner choice. It supports async/await, ensures proper context handling, and simplifies code.