Task Factory and,Task Parallelism (Task Parallel Library) in C#

Represented by:

• System.Threading.Tasks.TaskFactory which has no return type object.
• System.Threading.Tasks.TaskFactory<TResult> which has TResult as return type.

Important Note:

• Runs the task immediately after creating the task .This type of execution is known as Task Parallelism.
  
  
• Runs the task in a pre-defined order. This type of execution is known as Continuation Tasks.
  
  
• Running the task by pair. That is in Asynchronous programming model.

Now let’s look deep into Task Parallelism.

• Task parallel library is used to perform asynchronous operation.
  
  
• The task that are invoked by Task Parallelism is invoked by are independent of one another.
  

  Parallel.Invoke(() => Console.WriteLine("Perform Operatrion 1"), () =>Console.WriteLine("Perform Operatrion 2"));

• The Task are separated by “,”. They are independent of one another.
  
  
• These task are actually queued in ThreadPool.
  
  
• It provides many enhancements such as waiting, cancellation, continuations, exception handling, detailed status, custom scheduling, and more.
  
  
• It takes Action delegate as input, that is the return type is always void.
  
  
• Task.Run method create and start a task in one operation, that is in one step.
  
  
• TaskFactory.StartNew is also used to create and start a task in one operation.

Code sample

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Task_Parallel_Library {
    class Program {
        static void Main(string[] args) {
            runoperation obj = new runoperation();
            Console.WriteLine("Creating and running tasks implicitly");
            obj.parallelinvoke_implicitly();
            Console.WriteLine();
            Console.WriteLine("Creating and running tasks explicity");
            obj.parallelinvoke_explicity_01();
            Console.WriteLine();
            Console.WriteLine("Creating and running tasks explicity by referencing action delegate");
            obj.parallelinvoke_explicity_03();
            Console.ReadLine();
        }
    }
    class runoperation {
        static runoperation() {}
        public void parallelinvoke_implicitly() {
            //Creating and running tasks implicitly
            // This way of running mutiple task at same time is known as implicit task
            // both operation are exxecuted parallelly
            //Retun type is always void for parallel invoke. In technical term the input of parallel invoke is always action delegate
            Parallel.Invoke(() = > Console.WriteLine("Perform Operatrion 1"), () = > Console.WriteLine("Perform Operatrion 2"));
        }
        public void parallelinvoke_explicity_01() {
            Parallel.Invoke(() = > dowork("Task- One"), () = > dowork("Task- Two"), () = > dowork("Task- Three"));
        }
        private void dowork(string input) {
            Console.WriteLine("I have been called by '{0}'", input);
        }
        public void parallelinvoke_explicity_03() {
            // parallel invoke with action delegate as input
            Parallel.Invoke(action1);
        }
        /// <summary>
        /// Following is an action delegate with one input of type string
        /// </summary>
        Action action1 = new Action(delegate {
            Console.WriteLine("Hi.... I am action Delegate.... I am inline coded with anonymous type");
        });
    }
}