Force removing object from memory

Question

How can i delete object even it has references(c# or Java)?

For example:

void Main()
{
    var f = new Foo();
    var person = f.GetPerson();

}

public class Foo
{
    private object _person;

    public Foo()
    {
        _person = new object();
    }

    public object GetPerson()
    {  
         return _person;
    }
}

I want to delete _person from memory how can i do it?

`_person = null;` makes _person eligible for garbage collection, but you can't ever be sure when the garbage collector will remove it from memory — PermGenError, May 17 '13 at 11:01
@PermGenError unfortunally i havent access to _person from Main method. — Neir0, May 17 '13 at 11:02
@PermGenError _person is private field if i make a possible to change it from outer code(not from Foo) then is not better to make it public? — Neir0, May 17 '13 at 11:05
What are you actually trying to achieve. If you explain the problem more clearly, with a broader scope, people might be able to help. — Will Calderwood, May 17 '13 at 11:05
@Will Calderwood i want to delete object but i donnt know what is linked to him. How can i found all links and set them to null? — Neir0, May 17 '13 at 11:14
you can use JNDI and to pass the object to C method wich will deallocate the object from the memory — Jordan Borisov, May 17 '13 at 11:15
@Neir0 Edit the question and add that information. Then hopefully someone will be able to answer. — Will Calderwood, May 17 '13 at 11:24
@Neir0 A quick Google and I found this. http://stackoverflow.com/questions/1786985/get-active-references-to-an-object — Will Calderwood, May 17 '13 at 11:27

score 11 · Accepted Answer · edited May 23 '17 at 12:14

You can't, briefly.

If you did want to achieve something similar, you could reference your Person via a proxy, and pass the proxy around. So you could set the underlying Person reference to null (simply indicating the object is available for removal - not forcing its removal), but the clients would still contain a proxy reference.

You may want to check out Java SoftReferences and WeakReferences, which are related, and can trash objects during garbage collection cycles, despite their weak/soft references being available elsewhere.

score 1 · Answer 2 · answered May 17 '13 at 11:05

1

You can't remove an object from memory with reference in a managed language.

You can remove it from memory in C# by setting the reference to Null and calling GC.Collect()

answered May 17 '13 at 11:05

Will Calderwood

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Marko Topolnik · Answer 3 · 2013-05-17T12:08:55.377

Basically, you want to invalidate a living reference. This would break the key assumption of languages with automatic memory management, which is the impossibility of derefencing invalid pointers. At least in Java this is surely impossible and I invite a C# expert to contribute to this community wiki with C#-specific information.

Towards the solution of your requirement: you must encapsulate the reference to your object inside another one and never let the reference escape, so as to ensure 100% ownership of that reference. So the outside object will need to have the complete API of the inside object replicated, basically the Decorator pattern.

If you do that, you'll have the option to set the internal reference to null at any time and thus reliably release the object.

Force removing object from memory

3 Answers3