垃圾收集/链表

Question

Will the garbage collector (in theory) collect a structure like this?

package main

type node struct {
    next *node
    prev *node
}

func (a *node) append(b *node) {
    a.next = b
    b.prev = a
}

func main() {
    a := new(node)
    b := new(node)
    a.append(b)
    b = nil
    a = nil
}

This should be a linked list. a points to b, b points back to a. When I remove the reference in a and b (the last two lines) the two nodes are not accessible any more. But each node still has a reference. Will the go garbage collector remove these nodes nonetheless?

(Obviously not in the code above, but in a longer running program).

Is there any documentation on the garbage collector that handles these questions?

Answer 1

The set of garbage collector (GC) roots in your program is {a, b}. Setting all of them to nil makes all heap content eligible for collection, because now all of the existing nodes, even though they are referenced, are not reachable from any root.

The same principle guarantees also for example that structures with circular and/or self references get collected once they become not reachable.