Log Message:
Update to 1.4.22:

Bugfix maintenance release. Fixes to hash table expansion now
completely hang all threads very briefly while the hash table
pointers are swapped. Once swapped, it unlocks and uses locks as
normal.

In previous versions, the hash table was switched to a global lock
instead of a map of bucket-locks during expansion. This should be
faster overall with a small latency penalty. It's possible to
presize the hash table with -o hashpower