565974 - generators need not be rooted by call/args objects when closed

Status: RESOLVED WONTFIX

(Core :: JavaScript Engine, defect)

Description

[Luke Wagner [:luke]]

Although this isn't the biggest source of garbage in the world, I noticed, in situations where a generator creates an escaping closure that requires a scope chain:

function f() {
  var x = 3;
  g = function() { return x }
  ++x;
}

that after the generator is closed, it is still marked by its call and args objects, since we don't call fp->putActivationObjects() in SendToGenerator.  (This is true before and after the change in bug 540706.)  If we did call fp->putActivationObjects(), the private field of activation objects would be null and the generator would be free to be GC'd (assuming it wasn't rooted elsewhere).

Not a really big deal though...

Comment 1

[Dave Herman [:dherman]]

Nit: your example isn't actually a generator. Quick patch:

function f() {
  if (false) { yield }
  var x = 3;
  g = function() { return x }
  ++x;
}

Dave

Comment 2

[Luke Wagner [:luke]]

Hah, good point.