Slow down stdout

slower.py

#!/usr/bin/env python

import gevent.monkey; gevent.monkey.patch_all()

import os.path
import sys
import tempfile
import threading
import time

import gevent

lines_per_second = float(sys.argv[1])
wait_time = 1 / lines_per_second

tmpdir = tempfile.mkdtemp()
streaming_file = os.path.join(tmpdir, "slow-down")


def stdout_writer(stop_event):
    with open(streaming_file, "rb") as stream:
        while True:
            for line in stream.readlines():
                sys.stdout.write(line)
                time.sleep(wait_time)
            if stop_event.is_set():
                break

try:
    stop_event = threading.Event()
    with open(streaming_file, "ab") as stream:
        writer = gevent.spawn(stdout_writer, stop_event)
        for line in sys.stdin.readlines():
            stream.write(line)
    stop_event.set()
    writer.join()
except KeyboardInterrupt:
    sys.exit(1)