Csaba Henk <csaba / phony_for_avoiding_spam.org> writes: > Is "$a ||= 1" thread safe? I'd guess so, as "||=" is one piece of It is not guaranteed to be thread-safe, although in current official ruby vm it is 'atomic'. > Is it just an accident, or we can know somehow that this code is thread > safe? Where do the limits of thread safety lie? Treat it as an accident and don't depend on this behaviour. You should synchronise access to shared resources. > Csaba Yours, YS.