Csharp/CSharp Tutorial/Development/GC

Clean up gen 0

<source lang="csharp">using System; public class MyClass : IDisposable {

 ~MyClass()
 {
   Console.WriteLine("In destructor!");
 }
 
 public void Dispose()
 {
   Console.WriteLine("In Dispose() for {0}!");
   GC.SuppressFinalize(this);
 }

} public class MainClass {

 public static void Main(string[] args)
 {    
   MyClass c1, c2, c3, c4;
   c1 = new MyClass();
   c2 = new MyClass();
   c3 = new MyClass();
   c4 = new MyClass();
   
   Console.WriteLine("\n***** Disposing c1 and c3 *****");
   c1.Dispose();
   c3.Dispose();
   Console.WriteLine("***** Sweaping gen 0 *****");
   GC.Collect(0);  
   Console.WriteLine("\n***** New generations *****");
   Console.WriteLine("C1 is gen {0}", GC.GetGeneration(c1));
   Console.WriteLine("C2 is gen {0}", GC.GetGeneration(c2));
   Console.WriteLine("C3 is gen {0}", GC.GetGeneration(c3));
   Console.WriteLine("C4 is gen {0}", GC.GetGeneration(c4));
 }

}</source>

***** Disposing c1 and c3 *****
In Dispose() for {0}!
In Dispose() for {0}!
***** Sweaping gen 0 *****
***** New generations *****
C1 is gen 1
C2 is gen 1
C3 is gen 1
C4 is gen 1
In destructor!
In destructor!

Display current generations

<source lang="csharp">using System; public class MyClass : IDisposable {

 ~MyClass()
 {
   Console.WriteLine("In destructor!");
 }
 
 public void Dispose()
 {
   Console.WriteLine("In Dispose() for {0}!");
   GC.SuppressFinalize(this);
 }

} public class MainClass {

 public static void Main(string[] args)
 {    
   MyClass c1, c2, c3, c4;
   c1 = new MyClass();
   c2 = new MyClass();
   c3 = new MyClass();
   c4 = new MyClass();
   
   Console.WriteLine("\n***** Displaying generation of cars *****");
   Console.WriteLine("C1 is gen {0}", GC.GetGeneration(c1));
   Console.WriteLine("C2 is gen {0}", GC.GetGeneration(c2));
   Console.WriteLine("C3 is gen {0}", GC.GetGeneration(c3));
   Console.WriteLine("C4 is gen {0}", GC.GetGeneration(c4));
 }

}</source>

***** Displaying generation of cars *****
C1 is gen 0
C2 is gen 0
C3 is gen 0
C4 is gen 0
In destructor!
In destructor!
In destructor!
In destructor!

Forced garbage collection

<source lang="csharp">using System; class Junk {

 public Junk()
 {
   Console.WriteLine("Created Junk");
 }
 ~Junk()
 {
   Console.WriteLine("Destroyed Junk");
 }

} class MainClass {

 public static void Main() 
 {
   Junk j = new Junk();
   j = null;
   GC.Collect();
 }

}</source>

Created Junk
Destroyed Junk

Garbage collection type

<source lang="csharp">using System; using System.Collections.Generic; using System.Globalization; using System.IO; using System.Text; using System.Security.Cryptography; public class MainClass {

   public static void Main()
   {
       Console.WriteLine("TotalMemory: {0}", GC.GetTotalMemory(false));
       Console.WriteLine("(forcing a GC...)");
       GC.Collect();
       Console.WriteLine("TotalMemory: {0}", GC.GetTotalMemory(false));
   }

}</source>

TotalMemory: 141036
(forcing a GC...)
TotalMemory: 153444

Get total memory

<source lang="csharp">using System; using System.Collections.Generic; using System.Globalization; using System.IO; using System.Text; using System.Security.Cryptography; public class MainClass {

   public static void Main()
   {
       Console.WriteLine("TotalMemory: {0}", GC.GetTotalMemory(false));
       Console.WriteLine("(forcing a GC...)");
       GC.Collect();
       Console.WriteLine("TotalMemory: {0}", GC.GetTotalMemory(false));
   }

}</source>

TotalMemory: 141036
(forcing a GC...)
TotalMemory: 153444

weak references

<source lang="csharp">using System; using System.Collections.Generic; using System.Globalization; using System.IO; using System.Text; using System.Security.Cryptography; public class MainClass {

   public static void Main()
   {
       object target = new object();
       WeakReference wr = new WeakReference(target);
       Console.WriteLine("IsAlive: {0}", wr.IsAlive);
       GC.Collect();
       Console.WriteLine("IsAlive: {0}", wr.IsAlive);
   }

}</source>

IsAlive: True
IsAlive: False