Thanks. This is actually one of the topics I really want to tackle next.

If we just wrap every API call with synchronized, I'd expect heavy contention (some adaptive spinning and then OS-level park/unpark), so it'll likely bottleneck pretty quickly.

Doing something closer to ConcurrentHashMap (locking per bin rather than globally) could mitigate that.

For the open-addressing table itself, I'm also considering adding lightweight locking at the group level (e.g., a small spinlock per group) so reads stay cheap and writes only lock a narrow region along the probe path.