How to use Parallel Loops in C# how it improves performance??

This example shows how to use a Parallel.ForEach loop to enable data parallelism over anySystem.Collections.IEnumerable or System.Collections.Generic.IEnumerable<T> data source.

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using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Diagnostics; namespace ParallelLoopSample { class Program { static void Main(string[] args) { List<string> Large_List1 = new List<string>(); List<string> Large_List2 = new List<string>(); Object myList = new Object(); //Time taken by Loop to Write to List1 var watch1 = Stopwatch.StartNew(); for (Int64 i = 0; i <= 10000000; i++) { Large_List1.Add(i.ToString()); } watch1.Stop(); var elapsedMs = watch1.ElapsedMilliseconds; Console.WriteLine("Total Time Taken to Finish Loop1:{0}", elapsedMs); //Time Taken by Loop to Read List1 and Write to List2 var watch2 = Stopwatch.StartNew(); Parallel.ForEach(Large_List1, new ParallelOptions() { MaxDegreeOfParallelism = 10 }, sel => { try { lock (myList) { Large_List2.Add(sel); } } catch (Exception ex) { Console.WriteLine(ex.ToString()); } }); watch2.Stop(); var elapsedMs2 = watch2.ElapsedMilliseconds; Console.WriteLine("Total Time Taken to Finish Loop2:{0}", elapsedMs2); Console.ReadLine(); } } }

Output:

Grouping List using Linq

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using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace GroupingValues { public class Employee { public int EmpId; public string EmpName; public int LocationID; public string EmpDeptName; } class Program { static void Main(string[] args) { List<Employee> EmpList = new List<Employee>(); //Add IT Employees for(int i = 0; i<50;i++) { if(i < 10) EmpList.Add(new Employee { EmpId = i, EmpName = "ITDeptEmp" + i.ToString(), LocationID = 1, EmpDeptName = "Information Technology" }); else EmpList.Add(new Employee { EmpId = i, EmpName = "ITDeptEmp" + i.ToString(), LocationID = 2, EmpDeptName = "Information Technology" }); } //Add HR Employees for (int i = 50; i < 60; i++) { if(i<55) EmpList.Add(new Employee { EmpId = i, EmpName = "HRDeptEmp" + i.ToString(), LocationID = 2, EmpDeptName = "Human Resource" }); else EmpList.Add(new Employee { EmpId = i, EmpName = "HRDeptEmp" + i.ToString(), LocationID = 3, EmpDeptName = "Human Resource" }); } //Add Accounts Employees for (int i = 60; i < 70; i++) { EmpList.Add(new Employee { EmpId = i, EmpName = "AccountsDeptEmp" + i.ToString(), LocationID = 3, EmpDeptName = "Accounts" }); } //Now Group Employees by Department var EmployeeByDeptName = EmpList.ToLookup(x => x.EmpDeptName); foreach (IGrouping<string, Employee> Employee in EmployeeByDeptName) { Console.WriteLine("EMployees in {0} Department", Employee.Key); List<Employee> lstsGroupEmployee = new List<Employee>(); lstsGroupEmployee = Employee.Select(item => item).ToList<Employee>(); foreach (Employee Emp in lstsGroupEmployee) { Console.WriteLine("EmployeeID:{0},EmployeeName:{1}", Emp.EmpId, Emp.EmpName); } } //Now Group Employees by Location ID var EmployeeByLoc= EmpList.ToLookup(x => x.LocationID); foreach (IGrouping<int, Employee> Employee in EmployeeByLoc) { Console.WriteLine("EMployees in {0} Location", Employee.Key); List<Employee> lstsGroupEmployee = new List<Employee>(); lstsGroupEmployee = Employee.Select(item => item).ToList<Employee>(); foreach (Employee Emp in lstsGroupEmployee) { Console.WriteLine("EmployeeID:{0},EmployeeName:{1}", Emp.EmpId, Emp.EmpName); } } Console.ReadLine(); } } }

Output:

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EMployees in Information Technology Department EmployeeID:0,EmployeeName:ITDeptEmp0 EmployeeID:1,EmployeeName:ITDeptEmp1 EmployeeID:2,EmployeeName:ITDeptEmp2 EmployeeID:3,EmployeeName:ITDeptEmp3 EmployeeID:4,EmployeeName:ITDeptEmp4 EmployeeID:5,EmployeeName:ITDeptEmp5 EmployeeID:6,EmployeeName:ITDeptEmp6 EmployeeID:7,EmployeeName:ITDeptEmp7 EmployeeID:8,EmployeeName:ITDeptEmp8 EmployeeID:9,EmployeeName:ITDeptEmp9 EmployeeID:10,EmployeeName:ITDeptEmp10 EmployeeID:11,EmployeeName:ITDeptEmp11 EmployeeID:12,EmployeeName:ITDeptEmp12 EmployeeID:13,EmployeeName:ITDeptEmp13 EmployeeID:14,EmployeeName:ITDeptEmp14 EmployeeID:15,EmployeeName:ITDeptEmp15 EmployeeID:16,EmployeeName:ITDeptEmp16 EmployeeID:17,EmployeeName:ITDeptEmp17 EmployeeID:18,EmployeeName:ITDeptEmp18 EmployeeID:19,EmployeeName:ITDeptEmp19 EmployeeID:20,EmployeeName:ITDeptEmp20 EmployeeID:21,EmployeeName:ITDeptEmp21 EmployeeID:22,EmployeeName:ITDeptEmp22 EmployeeID:23,EmployeeName:ITDeptEmp23 EmployeeID:24,EmployeeName:ITDeptEmp24 EmployeeID:25,EmployeeName:ITDeptEmp25 EmployeeID:26,EmployeeName:ITDeptEmp26 EmployeeID:27,EmployeeName:ITDeptEmp27 EmployeeID:28,EmployeeName:ITDeptEmp28 EmployeeID:29,EmployeeName:ITDeptEmp29 EmployeeID:30,EmployeeName:ITDeptEmp30 EmployeeID:31,EmployeeName:ITDeptEmp31 EmployeeID:32,EmployeeName:ITDeptEmp32 EmployeeID:33,EmployeeName:ITDeptEmp33 EmployeeID:34,EmployeeName:ITDeptEmp34 EmployeeID:35,EmployeeName:ITDeptEmp35 EmployeeID:36,EmployeeName:ITDeptEmp36 EmployeeID:37,EmployeeName:ITDeptEmp37 EmployeeID:38,EmployeeName:ITDeptEmp38 EmployeeID:39,EmployeeName:ITDeptEmp39 EmployeeID:40,EmployeeName:ITDeptEmp40 EmployeeID:41,EmployeeName:ITDeptEmp41 EmployeeID:42,EmployeeName:ITDeptEmp42 EmployeeID:43,EmployeeName:ITDeptEmp43 EmployeeID:44,EmployeeName:ITDeptEmp44 EmployeeID:45,EmployeeName:ITDeptEmp45 EmployeeID:46,EmployeeName:ITDeptEmp46 EmployeeID:47,EmployeeName:ITDeptEmp47 EmployeeID:48,EmployeeName:ITDeptEmp48 EmployeeID:49,EmployeeName:ITDeptEmp49 EMployees in Human Resource Department EmployeeID:50,EmployeeName:HRDeptEmp50 EmployeeID:51,EmployeeName:HRDeptEmp51 EmployeeID:52,EmployeeName:HRDeptEmp52 EmployeeID:53,EmployeeName:HRDeptEmp53 EmployeeID:54,EmployeeName:HRDeptEmp54 EmployeeID:55,EmployeeName:HRDeptEmp55 EmployeeID:56,EmployeeName:HRDeptEmp56 EmployeeID:57,EmployeeName:HRDeptEmp57 EmployeeID:58,EmployeeName:HRDeptEmp58 EmployeeID:59,EmployeeName:HRDeptEmp59 EMployees in Accounts Department EmployeeID:60,EmployeeName:AccountsDeptEmp60 EmployeeID:61,EmployeeName:AccountsDeptEmp61 EmployeeID:62,EmployeeName:AccountsDeptEmp62 EmployeeID:63,EmployeeName:AccountsDeptEmp63 EmployeeID:64,EmployeeName:AccountsDeptEmp64 EmployeeID:65,EmployeeName:AccountsDeptEmp65 EmployeeID:66,EmployeeName:AccountsDeptEmp66 EmployeeID:67,EmployeeName:AccountsDeptEmp67 EmployeeID:68,EmployeeName:AccountsDeptEmp68 EmployeeID:69,EmployeeName:AccountsDeptEmp69 EMployees in 1 Location EmployeeID:0,EmployeeName:ITDeptEmp0 EmployeeID:1,EmployeeName:ITDeptEmp1 EmployeeID:2,EmployeeName:ITDeptEmp2 EmployeeID:3,EmployeeName:ITDeptEmp3 EmployeeID:4,EmployeeName:ITDeptEmp4 EmployeeID:5,EmployeeName:ITDeptEmp5 EmployeeID:6,EmployeeName:ITDeptEmp6 EmployeeID:7,EmployeeName:ITDeptEmp7 EmployeeID:8,EmployeeName:ITDeptEmp8 EmployeeID:9,EmployeeName:ITDeptEmp9 EMployees in 2 Location EmployeeID:10,EmployeeName:ITDeptEmp10 EmployeeID:11,EmployeeName:ITDeptEmp11 EmployeeID:12,EmployeeName:ITDeptEmp12 EmployeeID:13,EmployeeName:ITDeptEmp13 EmployeeID:14,EmployeeName:ITDeptEmp14 EmployeeID:15,EmployeeName:ITDeptEmp15 EmployeeID:16,EmployeeName:ITDeptEmp16 EmployeeID:17,EmployeeName:ITDeptEmp17 EmployeeID:18,EmployeeName:ITDeptEmp18 EmployeeID:19,EmployeeName:ITDeptEmp19 EmployeeID:20,EmployeeName:ITDeptEmp20 EmployeeID:21,EmployeeName:ITDeptEmp21 EmployeeID:22,EmployeeName:ITDeptEmp22 EmployeeID:23,EmployeeName:ITDeptEmp23 EmployeeID:24,EmployeeName:ITDeptEmp24 EmployeeID:25,EmployeeName:ITDeptEmp25 EmployeeID:26,EmployeeName:ITDeptEmp26 EmployeeID:27,EmployeeName:ITDeptEmp27 EmployeeID:28,EmployeeName:ITDeptEmp28 EmployeeID:29,EmployeeName:ITDeptEmp29 EmployeeID:30,EmployeeName:ITDeptEmp30 EmployeeID:31,EmployeeName:ITDeptEmp31 EmployeeID:32,EmployeeName:ITDeptEmp32 EmployeeID:33,EmployeeName:ITDeptEmp33 EmployeeID:34,EmployeeName:ITDeptEmp34 EmployeeID:35,EmployeeName:ITDeptEmp35 EmployeeID:36,EmployeeName:ITDeptEmp36 EmployeeID:37,EmployeeName:ITDeptEmp37 EmployeeID:38,EmployeeName:ITDeptEmp38 EmployeeID:39,EmployeeName:ITDeptEmp39 EmployeeID:40,EmployeeName:ITDeptEmp40 EmployeeID:41,EmployeeName:ITDeptEmp41 EmployeeID:42,EmployeeName:ITDeptEmp42 EmployeeID:43,EmployeeName:ITDeptEmp43 EmployeeID:44,EmployeeName:ITDeptEmp44 EmployeeID:45,EmployeeName:ITDeptEmp45 EmployeeID:46,EmployeeName:ITDeptEmp46 EmployeeID:47,EmployeeName:ITDeptEmp47 EmployeeID:48,EmployeeName:ITDeptEmp48 EmployeeID:49,EmployeeName:ITDeptEmp49 EmployeeID:50,EmployeeName:HRDeptEmp50 EmployeeID:51,EmployeeName:HRDeptEmp51 EmployeeID:52,EmployeeName:HRDeptEmp52 EmployeeID:53,EmployeeName:HRDeptEmp53 EmployeeID:54,EmployeeName:HRDeptEmp54 EMployees in 3 Location EmployeeID:55,EmployeeName:HRDeptEmp55 EmployeeID:56,EmployeeName:HRDeptEmp56 EmployeeID:57,EmployeeName:HRDeptEmp57 EmployeeID:58,EmployeeName:HRDeptEmp58 EmployeeID:59,EmployeeName:HRDeptEmp59 EmployeeID:60,EmployeeName:AccountsDeptEmp60 EmployeeID:61,EmployeeName:AccountsDeptEmp61 EmployeeID:62,EmployeeName:AccountsDeptEmp62 EmployeeID:63,EmployeeName:AccountsDeptEmp63 EmployeeID:64,EmployeeName:AccountsDeptEmp64 EmployeeID:65,EmployeeName:AccountsDeptEmp65 EmployeeID:66,EmployeeName:AccountsDeptEmp66 EmployeeID:67,EmployeeName:AccountsDeptEmp67 EmployeeID:68,EmployeeName:AccountsDeptEmp68 EmployeeID:69,EmployeeName:AccountsDeptEmp69

GenericShape or Polygon Area Calculator in C#

Shape.cs

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using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace GenericAreaCalculator { public class Shape { public Dictionary<int,int> x; public Dictionary<int, int> y; public Shape() { x = new Dictionary<int, int>(); y = new Dictionary<int, int>(); } } }

Area.cs

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using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace GenericAreaCalculator { public class Area:Shape { public float CalculateArea(Shape Shapes,int sides) { float area = 0; int x1 = 0; int y2 = 0; int y1 = 0; int x2 = 0; if (sides > 1) { for (int index = 1; index < sides; index++) { x1 = Shapes.x[index]; y2 = Shapes.y[index + 1]; y1 = Shapes.y[index]; x2 = Shapes.x[index + 1]; area = area + (((x1 * y2)) - ((y1 * x2))); } int xn = Shapes.x[sides]; y1 = Shapes.y[1]; int yn = Shapes.y[sides]; x1 = Shapes.x[1]; area = (area + (((xn * y1)) - ((yn * x1))))/2; } else if (sides == 1) { area = (float)(3.14 * Shapes.x[0] * Shapes.x[0]); } return Math.Abs(area); } } }

Program.cs

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using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace GenericAreaCalculator { class Program { static void Main(string[] args) { Shape shapeobj = new Shape(); shapeobj.x.Add(1, 0); shapeobj.x.Add(2, 10); shapeobj.x.Add(3, 10); shapeobj.x.Add(4, 0); shapeobj.y.Add(1, 0); shapeobj.y.Add(2, 0); shapeobj.y.Add(3, 10); shapeobj.y.Add(4, 10); Area area = new Area(); float ShapeArea = area.CalculateArea(shapeobj, 4); Console.WriteLine("Area of Square is:{0}", ShapeArea); shapeobj.x.Clear(); shapeobj.y.Clear(); shapeobj.x.Add(0, 10); ShapeArea = area.CalculateArea(shapeobj, 1); Console.WriteLine("Area of Circle is:{0}", ShapeArea); Console.ReadLine(); } } }

Output:

Pseudo for using Observer Pattern to Notify Database Connection Across Multiple Threads

What is Observer Pattern ?

The observer design pattern enables a subscriber to register with and receive notifications from a provider. It is suitable for any scenario that requires push-based notification. The pattern defines a provider (also known as a subject or an observable) and zero, one, or more observers. Observers register with the provider, and whenever a predefined condition, event, or state change occurs, the provider automatically notifies all observers by calling one of their methods. In this method call, the provider can also provide current state information to observers. In the .NET Framework, the observer design pattern is applied by implementing the generic System.IObservable(Of T) and System.IObserver(Of T) interfaces. The generic type parameter represents the type that provides notification information.

Example :

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using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Data.SqlClient; namespace ObserverPatternDBHandler { class Program { static void Main(string[] args) { SqlConnection objconnection = new SqlConnection("Data Source=devserv,1499;Network Library=DBMSSOCN;Initial Catalog=dev;User ID=dev;Password=dev123;"); // Configure Observer pattern ConcreteSubject s = new ConcreteSubject(); s.Attach(new ConcreteObserver(s, "DBUsingThread1")); s.Attach(new ConcreteObserver(s, "DBUsingThread2")); s.Attach(new ConcreteObserver(s, "DBUsingThread3")); // Change subject and notify observers objconnection.Open(); s.SubjectState = objconnection.State==System.Data.ConnectionState.Open?true:false; s.Notify(); objconnection.Close(); s.SubjectState = objconnection.State == System.Data.ConnectionState.Open ? true : false; s.Notify(); // Wait for user Console.ReadKey(); } } abstract class Subject { private List<Observer> _observers = new List<Observer>(); public void Attach(Observer observer) { _observers.Add(observer); } public void Detach(Observer observer) { _observers.Remove(observer); } public void Notify() { foreach (Observer o in _observers) { o.Update(); } } } /// <summary> /// The 'ConcreteSubject' class /// </summary> class ConcreteSubject : Subject { private bool _subjectState; // Gets or sets subject state public bool SubjectState { get { return _subjectState; } set { _subjectState = value; } } } /// <summary> /// The 'Observer' abstract class /// </summary> abstract class Observer { public abstract void Update(); } /// <summary> /// The 'ConcreteObserver' class /// </summary> class ConcreteObserver : Observer { private string _name; private bool _observerState; private ConcreteSubject _subject; // Constructor public ConcreteObserver( ConcreteSubject subject, string name) { this._subject = subject; this._name = name; } public override void Update() { _observerState = _subject.SubjectState; Console.WriteLine("Observer {0}'s new state is {1}", _name, _observerState?"Connected":"Disconnected"); } // Gets or sets subject public ConcreteSubject Subject { get { return _subject; } set { _subject = value; } } } }

Output: