One possibility would be to reference a password variable always from t he same thread. But even if you use multiple threads referencing the same memory locatio

One possibility would be to reference a password variable always from t he same thread. But even if you use multiple threads referencing the same memory location, you could make some of them weak references (which the GC doesn't take into account when deleting the object) or you could make sure you stop referencing them in both threads and force the GC to run on that object. The destructor could handle the scrambling.