Path::Class::File::Lockable uses simple files to indicate whether a file is locked or not. It does not use flock(), since that is unstable over NFS. Effort has been made to avoid race conditions. Path::Class::File::Lockable is intended for long-standing locks, as in a Subversion workspace. See SVN::Class for example. WWW: https://metacpan.org/release/Path-Class-File-Lockable