faramir118/mangos — comment on commit 53ed5f371e887039902547ea680a1375219232e4
File:  line 0
By sixsixnine:

Load/unload are the only mutators of dtNavMesh.
Even they would not cause us problems if they were atomic, but what happens is, that searches try to use partially loaded tiles.

Locking ... I don't really like it since it mostly indicates design problem(s).
On the other side, its easy to implement.

If you going to do it, make sure to use readers–writer lock.