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home / developersection / forums / what is the difference between task.run(), task.factory.startnew() and thread?
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What is the difference between Task.Run(), Task.Factory.StartNew() and Thread?

Anubhav Sharma 963 19 Jun 2025

What is the difference between Task.Run(), Task.Factory.StartNew() and Thread?

c# c#
Updated 23 Jun 2025
Anubhav Sharma
Anubhav Sharma

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The Anubhav portal was launched in March 2015 at the behest of the Hon'ble Prime Minister for retiring government officials to leave a record of their experiences while in Govt service .

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1 Answers

Ponu Maurya
Ponu Maurya 23 Jun 2025
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In C#, Task.Run(), Task.Factory.StartNew(), and Thread all execute code concurrently, but they differ in abstraction level, use case, and behavior. Understanding these differences helps you choose the right tool for the job.

1. Thread – Low-Level Threading

  • Represents a physical OS thread.
  • Must be manually started.
  • Gives full control over thread lifetime.
  • Expensive in terms of memory and CPU.

Example:

Thread thread = new Thread(() => DoWork());
thread.Start();

Use When:

  • You need long-running, dedicated threads.
  • You require thread-level control (e.g., priority, abortion).

2. Task.Run() – Simplified Task-Based Concurrency

  • Queues the task to the ThreadPool.
  • High-level wrapper for asynchronous, parallel execution.
  • Optimized for CPU-bound or background work.
  • Returns a Task you can await.

Example:

await Task.Run(() => DoWork());

Use When:

  • You want to run code asynchronously without blocking.
  • You're doing short, CPU-bound operations in the background.

3. Task.Factory.StartNew() – Advanced Task Creation

  • Offers fine-grained control over task scheduling.
  • You can specify TaskCreationOptions, TaskScheduler, etc.
  • Less recommended since Task.Run() was introduced in .NET 4.5.

Example:

Task.Factory.StartNew(() => DoWork(), 
                      CancellationToken.None, 
                      TaskCreationOptions.DenyChildAttach, 
                      TaskScheduler.Default);

Use When:

You need control over task options, scheduling, or child tasks.

Key Differences Table

Feature Thread Task.Run() Task.Factory.StartNew()
Abstraction Level Low High Mid
Returns a Task? No Yes Yes
ThreadPool usage No (dedicated thread) Yes Yes (by default)
Control over scheduling Yes Minimal Full
Best for Long-running background work Short CPU-bound work Advanced scheduling needs
Supports await No Yes Yes
Memory cost High Low Low

Recommendations:

  • Use Task.Run() for most async or background work in modern apps.
  • Avoid Task.Factory.StartNew() unless you need advanced options.
  • Use Thread only when:
    • You need full control over the thread lifecycle.
    • You are building infrastructure like a custom thread pool.

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