Task.Run
Learn to push CPU-bound work to the background with Task.Run.
What is Task.Run?
Task.Run sends work to the thread pool and returns a Task at once. It is used to run heavy CPU work in the background so the main thread is freed.
Example: Task t = Task.Run(() => HeavyCompute());. The lambda runs on a pool thread; you wait for it with await t. Do not use Task.Run for input/output; just call an async method.
Task.Run vs await
Task.Run and await are different things. Task.Run starts a new pool thread; await waits for an already-running Task. They are often combined: await Task.Run(() => Work()).
But wrapping every async call in Task.Run is a common mistake. Async methods already run in the background; wrapping wastes a thread. Use Task.Run only for real CPU work.
Exercise Compute with Task.Run
Define static int Square(int n) returning n * n. Make Main a static async Task Main. Run the computation in the pool with int result = await Task.Run(() => Square(7)); and print it with Console.WriteLine(result);.
Show example solution
return n * n;. Make Main static async Task Main() and write int result = await Task.Run(() => Square(7)); Console.WriteLine(result);
Example solution:
using System;
using System.Threading.Tasks;
class Program
{
static int Square(int n)
{
return n * n;
}
static async Task Main()
{
int result = await Task.Run(() => Square(7));
Console.WriteLine(result);
}
}Test yourself
-
Match the concepts
- Task.Run
- Sends work to the pool
- await task
- Waits for the work to finish
- CPU work
- Suitable for Task.Run
- I/O work
- Call an async method directly
-
When is Task.Run used?
- To wrap every async call
- When reading from the network
- To run heavy CPU computations in the background
- When saving a file
Show answer
To run heavy CPU computations in the background — Correct. Task.Run is for heavy CPU work in the background.
-
Complete the Task.Run call
Task t = Task.____(() => Work());Show answer
Task t = Task.Run(() => Work());