libfile-fcntllock-perl 0.22-1build1 (amd64 binary) in ubuntu vivid

 File::FcntlLock is a Perl module to do file locking in an object oriented
 fashion using the fcntl(2) system call. This allows locks on parts of a file
 as well as on the whole file and overcomes some known problems with flock(2),
 on which Perl's flock() function is based.
 .
 Furthermore due to its design it supports reliable locking over NFS.