Question

I am eager to know what happens to a object in .NET when it falls out of scope. Something like this:

class A
{
    ClassB myObjectB = new ClassB();
}
//what happens to object at this point here?

What happens in the memory? Does GC get called when it falls out of scope and loose it reference in the heap?

Answer 1

What happens in the memory? Does GC get called when it falls out of scope and loose it reference in the heap?

No – the GC doesn’t get called at this point.

What happens is that the object is left in memory, but is now “unrooted” – basically, there are no references to that object from any other object. As such, the object is now eligible for garbage collection.

At some point in the future, the GC will run. When this happens, the unrooted object will now be eligible for garbage collection. Depending on which generation holds the object, it may or may not be cleaned at that point. Eventually, if the program continues executing and if memory pressure causes the appropriate generation to be collected, the memory for that object will be reclaimed.

There is no definite point in time when this will happen (unless you explicitly call GC.Collect, which is a bad idea). However, with managed code, you don’t really need to worry about when this will happen. Just assume that it will happen when and if appropriate for your specific application.