I was thinking the same. There are many mutexes out there, some are better at certain workloads than the rest. DistributedMutex and SharedMutex come to mind (https://github.com/facebook/folly/blob/main/folly/synchroniz..., https://github.com/facebook/folly/blob/main/folly/SharedMute...) Just like hashmaps, it's rarely the case that a single hashmap is better under _all_ possible workloads.