thedarkone2 / gmail.com wrote: > I am all for addition of `ConcurrentHash` or `Concurrent::Array` (these > new data structures would have `cas` and `swap` methods), but for > performance reasons plain old `Hash` and `Array` should be kept > completely un-thread-safe. Does that mean segfaulting the VM on concurrent Hash or Array access is OK? I don't think any current Ruby VM allows that. If we need to prevent segfaults on concurrent access, I suspect we'll need to pay some concurrency costs. Personally, I'm OK if we allow the VM to segfault on concurrent accesses, but I doubt others will agree with me.