Running a process and use input and output (with reader thread) in Python

main.py

from subprocess import PIPE, Popen, run
from threading import Thread
from time import sleep

try:
  from queue import Queue, Empty
except ImportError:
  from Queue import Queue, Empty  # python 2.x
    
out_q = Queue()
err_q = Queue()

def enqueue_output(out, q):
  for line in iter(out.readline, ""):
    q.put_nowait(line)
  out.close()

def readline(q = out_q, timeout:int|None=30) -> str:
  '''Read line from stream queue.
  :param timeout: timeout is None (the default), block if necessary until an item is available.\
  If timeout is a positive number, it blocks at most timeout seconds and raises the Empty exception\
  if no item was available within that time. read more: https://docs.python.org/3/library/queue.html#queue.Queue.get
  '''
  line = q.get(True, timeout)

def exec_proc(*args)->tuple[Popen, Thread, Thread]:
  '''Execute a process, start reader threads and return Popen instance'''
  proc = Popen(args,
               stdout=PIPE,
               stderr=PIPE,
               stdin=PIPE,
               encoding="utf-8")
  Thread(target=enqueue_output, args=(proc.stdout, out_q), daemon=True).start()
  Thread(target=enqueue_output, args=(proc.stderr,err_q), daemon=True).start()
  return proc

proc = exec_proc("ssh", "-i", "mykey", "bsimjoo@somewhe.re")

def writeline(*lines: str, end="\n", sep=" "):
  if proc.poll() is not None:
    return False
  line = sep.join(lines) + end
  proc.stdin.write(line)
  return True

if proc.poll() is None:
  # process is alive! keep going
  try:
    while True:
      line = readline(timeout=1)
      print(line)
  except:
    pass
  r = writeline("echo hello")
  if r:
    print(readline())
  proc.kill()