Garbage Collector in .NET


many times in interview the interviewer asked what is garbage collector in .net ? at that time candidated may be get trouble to answer so by considering above requirement i have written this blog specially focusing on new comer's. so let us start with basics
Role of Grabage collector in .Net

 Garbage Collector is available in CLR of .net framework and it is responsible for complete memory management for the .net  applications.

Allocating memory for the objects and de allocation of memory when their life time is completed is the responsibility of garbage collector.

Various steps performed by garbage collector when it was invoked are as follows.

  •  Suspends all the threads in .net application and it will run on a separate thread.
  • It draws a graph of all reachable objects. An object that contains a reference to heap memory area is called as reachable object and the object that contains null is called as unreachable object. All the objects that are not in the graph will be unreachable objects.

  •  All unreachable objects with a destructor will be added to a queue called Freachable queue

  • All unreachable objects without a destructor are destroyed and all reachable objects will be moved down the heap to make free memory available at the top of the heap. While moving reachable objects down the heap, garbage collector will update the objects to refer to new memory location.
  • Resumes the threads of the .net application.
  • Destroys all unreachable objects with a destructor available in freachable queue.


Garbage collector will be invoked only in the following two situations.

1.When there is no sufficient memory for new objects.

2.When the application execution comes to an end

If you want to invoke the garbage collector manual then call the collect() method of GC class available in .net framework.


I hope this blog is useful for all readers,if you have any suggestion then please contact me.

Next Recommended Reading Introduction to CLR in .Net framework.