The "counter" here is an RWMutex (or RWSpinLock). You can't really make it distributed while guaranteeing mutual exclusion [1]. You could use an hashmap with mo

The "counter" here is an RWMutex (or RWSpinLock). You can't really make it distributed while guaranteeing mutual exclusion [1]. You could use an hashmap with more fine grained locking, but to deal with rehashing you end up reinventing something like ArcSwap anyway. [1] True no-writes-on-shared-locking RWMutexes do exist, but are significantly more complex and require epoch detection like the ArcSwap, so there is no significant advantage.