Package lockfile handles pid file based locking.
 .
 While a sync.Mutex helps against concurrency issues within a single process,
 this package is designed to help against concurrency issues between
 cooperating processes or serializing multiple invocations of the same process.
 You can also combine sync.Mutex with Lockfile in order to serialize an action
 between different goroutines in a single program and also multiple invocations
 of this program.