Why can .NET not have memory leaks?

Question

Ignoring unsafe code, .NET cannot have memory leaks. I\'ve read this endlessly from many experts and I believe it. However, I do not understand why this is so.

It is

Answer 1

Here's an example of a memory leak in .NET, which doesn't involve unsafe/pinvoke and doesn't even involve event handlers.

Suppose you're writing a background service that receives a series of messages over a network and processes them. So you create a class to hold them.

class Message 
{
  public Message(int id, string text) { MessageId = id; Text = text; }
  public int MessageId { get; private set; }
  public string Text { get; private set; }
}

OK, so far so good. Later on you realize that some requirement in the system could sure be made easier if you had a reference to the previous message available when you do the processing. There could be any number of reasons for wanting this.

So you add a new property...

class Message
{
  ...
  public Message PreviousMessage { get; private set; }
  ...
}

And you write the code to set it. And, of course, somewhere in the main loop you have to have a variable to keep up with the last message:

  Message lastMessageReceived;

Then you discover some days later than your service has bombed, because it has filled up all the available memory with a long chain of obsolete messages.