3 ms·

> ran into the restrictions on collection visibility Is there any more information about this? It seems really subtle!

• pwdisswordfish9 5y ago
  Basically, looking at the target of a WeakRef makes it ineligible for collection until at least the next await, which the spec mandates by way of the [[KeptAlive]] list. This is meant to prevent TOCTOU bugs by foolish programmers doing this: if (weakref.deref()) { /* garbage collection here */ use(weakref.deref()); }
  • josefx 5y ago
    Isn't that a rather narrow case? What happens on the following, is that protected? if (weakref.deref()) { /* garbage collection here */ use(heavyComputations(), weakref.deref()); }
    • pwdisswordfish9 5y ago
      Yes, as long as there is no intervening suspension (await, or the script otherwise exiting to the event loop).