Async and Await Theory

What is Task in C#? ( ref: https://www.csharpstar.com/tasks-csharp/)

 

.NET framework provides Threading.Tasks class to let you create tasks and run them asynchronously. A task is an object that represents some work that should be done. The task can tell you if the work is completed and if the operation returns a result, the task gives you the result.

C# task object typically executes asynchronously on a thread pool thread rather than synchronously on the main application thread.

 

What is Thread?

 

.NET Framework has thread-associated classes in System.Threading namespace.  A Thread is a small set of executable instructions.

Why we need Tasks

 

It can be used whenever you want to execute something in parallel. Asynchronous implementation is easy in a task, using’ async’ and ‘await’ keywords.

Why we need a Thread

 

When the time comes when the application is required to perform few tasks at the same time.

 

Properties of Task Class:

Property	Description
Exception	Returns any exceptions that caused the task to end early
Status	Returns the Tasks status
IsCancelled	Returns true if the Task was cancelled
IsCompleted	Returns true if the task is completed successfully
IsFaulted	Returns true if the task is stopped due to unhandled exception
Factory	Provides acess to TaskFactory class. You can use that to create Tasks

 

Methods in Task Class :

Methods	Purpose
ConfigureAwait	You can use Await keyword for the Task to complete
ContinueWith	Creates continuation tasks.
Delay	Creates a task after specified amount of time
Run	Creates a Task and queues it to start running
RunSynchronously	Runs a task Synchronously
Start	Starts a task
Wait	Waits for the task to complete
WaitAll	Waits until all tasks are completed
WaitAny	Waits until any one of the tasks in a set completes
WhenAll	Creates a Task that completes when all specified tasks are completed
WhenAny	Creates a Task that completes when any specified tasks completes

 

How to create a Task

1. static void Main(string[] args) {  
2.     Task < string > obTask = Task.Run(() => (  
3.         return“ Hello”));  
4.     Console.WriteLine(obTask.result);  
5. } 

How to create a Thread

1. static void Main(string[] args) {  
2.     Thread thread = new Thread(new ThreadStart(getMyName));  
3.     thread.Start();  
4. }  
5. public void getMyName() {} 

Differences Between Task And Thread

 

Here are some differences between a task and a thread.

1. The Thread class is used for creating and manipulating a thread in Windows. A Task represents some asynchronous operation and is part of the Task Parallel Library, a set of APIs for running tasks asynchronously and in parallel.
2. The task can return a result. There is no direct mechanism to return the result from a thread.
3. Task supports cancellation through the use of cancellation tokens. But Thread doesn't.
4. A task can have multiple processes happening at the same time. Threads can only have one task running at a time.
5. We can easily implement Asynchronous using ’async’ and ‘await’ keywords.
6. A new Thread()is not dealing with Thread pool thread, whereas Task does use thread pool thread.
7. A Task is a higher level concept than Thread.
8. One of the major difference between task and thread is the propagation of exception. While using thread if we get the exception in the long running method it is not possible to catch the exception in the parent function but the same can be easily caught if we are using tasks.