#938 – Finding Out What GC Generation an Object Is In

The garbage collector (GC) groups objects into generations to avoid having to examine and collect all objects in memory whenever a garbage collection is done.

For debugging purposes, it’s sometimes useful to know which generation an object currently belongs to.  You can get this information using the GC.GetGeneration method, as shown below.

            Dog bob = new Dog("Bob", 5);
            Console.WriteLine(string.Format("Bob is in generation {0}", GC.GetGeneration(bob)));

            GC.Collect();
            Console.WriteLine(string.Format("Bob is in generation {0}", GC.GetGeneration(bob)));

            GC.Collect();
            Console.WriteLine(string.Format("Bob is in generation {0}", GC.GetGeneration(bob)));

In the example above, the “Bob” Dog object starts out in generation 0. After we do the first garbage collection, it’s promoted to generation 1 and after the 2nd collection, it’s promoted to generation 2.