The primary purpose of File::Tail is reading and analysing log files while
they are being written.

The module tries very hard NOT to ``busy-wait'' on a file that has little
traffic.  If the file does not get altered for a while, File::Tail gets
suspicious and startschecking if the file was truncated, or moved and
recreated. If anything like that had happened, File::Tail will quietly
reopen the file, and continue reading.