Python collections.deque is a fast FIFO that does not require thread locking as the more sophisticated queue.

Use deque to read the last line of files as follows.

from pathlib import Path
from collections import deque

fn = Path('myfile.txt')

with fn.open('r') as f:
    last = deque(f,1)[0]

last

last line of file. Throws IndexError if file is empty.

By changing 1 the last N lines of the file may be read and indexed.

deque examples