• name: _weakref
  • description: use module _weakref
  • command-line: –withmod-_weakref
  • command-line for negation: –withoutmod-_weakref
  • option type: boolean option
  • default: True

Use the ‘_weakref’ module, necessary for the standard lib ‘weakref’ module. PyPy’s weakref implementation is not completely stable yet. The first difference to CPython is that weak references only go away after the next garbage collection, not immediately. The other problem seems to be that under certain circumstances (that we have not determined) weak references keep the object alive.