When the tree on the disk is newer than the one in memory, the server will automatically reload the outdated tree. If the backing file is a symbolic link, it first checks whether it is pointing to the same file (reload if different), and then checks the timestamp of the linked file.
Pause new requests handling when reloading the trees, because TBB will hang in the child process if there are active workers when forked.
Reduce subtree extraction memory consumption by avoiding duplicating name maps.