Question

Suppose an object has a Finalize() method.

When it is first created, a pointer in the finalization queue was added.

The object has no references .

When a garbage collection occurs, it moves the reference from the finalization queue to the f-reachable queue and a thread is started to run the Finalize method (sequentially after other objects’ Finalize methods).

So the object now (after resurrection) has only one root which is the pointer from the f-reachable queue.

At this point, does/did the object get promoted to the next generation ?

Answer 1

This is something you can just try. Run this code in the Release build without a debugger attached:

using System;

class Program {
    static void Main(string[] args) {
        var obj = new Foo();
        // There are 3 generations, could have used GC.MaxGeneration
        for (int ix = 0; ix < 3; ++ix) {
            GC.Collect();
            GC.WaitForPendingFinalizers();
        }
        Console.ReadLine();
    }
}

class Foo {
    int attempt = 0;
    ~Foo() {
        // Don't try to do this over and over again, rough at program exit
        if (attempt++ < 3) {
            GC.ReRegisterForFinalize(this);
            Console.WriteLine(GC.GetGeneration(this));
        }
    }
}

Output:

1
2
2

So it stays in the generation it got moved to by the collection, moving to the next one on each collection until it hits the last one. Which makes sense in general.