refactor(server.go) No lock is needed when reading server variables in a internal function
Our server is a single routine for loop. We have a lock to avoid "data-race" between the external function calls and internal operations(writes). So we can drop the extra lock when reading variables internally.
Merge pull request #197 from xiangli-cmu/remove_extra_lock

refactor(server.go) No lock is needed when reading server variables in a internal function