its being stated there that Apache::Session::File provides locking with the help of files created in LockDirectory specified.My question is how they function internally . why does it create two files there.

when we read or write some data in session , how do we get access to session file through these lock files

why are two files created. what is their exact functionality in term of locking. what are all the things that i can do to prevent data corruption or loss between different requests.