019 C# Garbage Collcetion

Garbage collection
                   Garbage collection is a technique to recover the memory consumed by some unused variable and objects. When you create an instance of an object, some memory is allocated for the object .But when  the object is no longer usable, the memory remain occupied for the object. For example, we have created method, the method have two variable which hold two class instance. Now we call the method, the two variable consumes some space,  now the method call is over, what will be about the memory, consume by the two variable ?

public class student

  {

  }

public class school

  {

  }

public class show

{

     void GetFess()

      {

         student obj = new student();

        school obj1 = new school();

      }

}

                  Garbage collection works to clean up the objects memory. It is a low priority threat , and it is always running. Garbage collection process gates higher  priority,when  memories almost full. Garbage collection works with higher priority to clean up the memory and let the other priority works smoothly. Garbage collection is a continuous work.Garbage collection find the reference tree  before disposing any object, because an object could be reference to another object and system does not knows when any object will be called. In general case, an object containing high memory allocation, dispose method is written to dispose the object without garbage collection.

                  The dispose method free unmanage resources like files , database connection and com component. It belongs to IDdisposable Interface. Dispose method can be called . It is a pattern to dispose and object. This comes  with two overload, Dispose(), Dispose(Boolean). Dispose method cleanup all the object, second  overload, Dispose( Boolean) ,Boolean  indicate the method is coming from dispose method or not.Here is the example of dispose method.

 

public class Customer : IDisposable

{

          bool disposed = false;

          public void Dispose()

          {

            Dispose(true);

           GC.SuppressFinalize(this);

          }

          protected virtual void Dispose(bool disposing)

         {

          if (disposed)

           return;

           if (disposing)

          {

          }

         disposed = true;

     }

}

                   Garbage collection provided method call finalize .It free unmanage resources like database connection, files and com . Finalize method is held before it is destroyed. Example of finalized.

class Student

{

              public Student()

              {

                  Console.WriteLine("I am in Student");

              }

               ~Student()

              {

               Console.WriteLine("Destructor of Student");

             }

}

Here is some namespace , that provides Garbage Collection

• System.GC :

          Garbage collector,  automatically reclaims unused memory.Here is user of System.GC  class

      student obj = new student();

         // Return maximum number of genration

         Console.WriteLine(GC.MaxGeneration);

        // do collection

        GC.Collect();

      // do collection for 0 generation

       GC.Collect(0);

      // do collection upto 1 generation

      GC.Collect(0);

 

   // do collection upto 2 generation

     GC.Collect(2);

     //total allocated bytes

     Console.WriteLine(GC.GetTotalMemory(false));

• System.GCCollectionMode : Return behavior for a forced garbage collection , three mode

           are the

                  1) Default
                  2) Forced
                  3)Optimized

       GC.Collect(0, GCCollectionMode.Default);

           GC.Collect(0, GCCollectionMode.Forced);

           GC.Collect(0, GCCollectionMode.Optimized)

• System.GCNotificationStatus :

         Return  the current registration for notification of the next full garbage collection

     IndiCator = GC.WaitForFullGCComplete();

        if (IndiCator == GCNotificationStatus.Succeeded)

         {

            //Do some thiing

        }

        else if (IndiCator == GCNotificationStatus.Canceled)

       {

         //Do some thiing

      }

       else if (IndiCator == GCNotificationStatus.Timeout)

     {

       //Do some thiing

     }

      else if (IndiCator == GCNotificationStatus.Timeout)

     {

        //Do some thiing

    }

Circular reference : An object can be referred to another object, another object can be referred to another object. In such way, circular reference can be formed. Object containing  circular reference is very difficult to dispose. Reference tree of a circular reference point to each other. Garbage collection is wise enough to handle such type of problem. Garbage collection dispose both object which
pointed to each other.

public class student

{

            school b;

            public student(school b)

           {

             this.b = b;

         }

}

public class school

{

       student a;

      public school(student b)

      {

        this.a = b;

     }

}