CODEWITHSUNDEEP
c#.netgarbage-collection
Larry Lustig
Larry Lustig

Reputation: 50970

If I reference an object property of an object that goes out of scope is the outer object eligible to be garbage collected?

In the following code:

public class MyClass
{

    public SmallObject SmallThing { get; set; }

    private void MyMethod()
    {
        var largeThing = new LargeObject();
        SmallThing = largeThing.SmallThing;
    }

}

after MyMethod() has executed I have a reference to SmallThing but no reference to largeThing. Is Dot Net able to recognize that largeThing is eligible to be collected while the SmallObject instance it contained is not so eligible? Or does Dot Net somehow remember the original association between largeThing and SmallThing? (You may assume that SmallThing does not contain an explicit backward reference to largeThing created by the programmer).

Upvotes: 1

Views: 68

Answers (2)

Scott Chamberlain
Scott Chamberlain

Reputation: 127563

You are correct, largeThing will be collectable as soon as you pass the line 

SmallThing = largeThing.SmallThing;

it does not need to even wait for MyMethod to return for it to be able to collect it (This assumes running release mode without the debugger attached). As soon as the last useage of largeThing is passed it will be eligible for collection.

Upvotes: 1

D Stanley
D Stanley

Reputation: 152566

Since there are no active references to largeThing it will be eligible for garbage collection. There are no "hidden" or implicit references back from SmallThing that would keep it from being eligible.

Upvotes: 1

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