Read tornado.process.Subprocess stdout

countdown.sh

#!/bin/bash

sleep_sec=0

usage() {
    echo "Usage: $0 [-s sleep_sec] <num>"
}

while getopts :s:h OPT; do
    case $OPT in
        s)  sleep_sec=$OPTARG
            ;;
        h)  usage
            exit
            ;;
        \?) usage 1>&2
            exit 1
            ;;
    esac
done

shift $((OPTIND - 1))

if [ -z "$1" ]; then
    usage 1>&2
    exit 1
fi

set -eu

for i in $(seq $1); do
    sleep $sleep_sec
    echo $(($1 - $i))
done

tornado_subproc_stream_read.py

# -*- coding: utf-8 -*-

from __future__ import absolute_import, division, print_function

import logging
import os
import shlex
from tornado import gen
from tornado.ioloop import IOLoop
from tornado.process import Subprocess
from tornado.log import enable_pretty_logging
from tornado.iostream import StreamClosedError

command = '{0}/countdown.sh -s 1 5'.format(os.getcwd())


@gen.coroutine
def run_subproc():
    proc = Subprocess(shlex.split(command), stdout=Subprocess.STREAM)
    try:
        while True:
            line = yield proc.stdout.read_until(b'\n')
            logging.info('read: %s', line.decode('ascii')[:-1])
    except StreamClosedError:
        pass
    except Exception as e:
        logging.error('Error: %s', e)
    finally:
        IOLoop.current().stop()


if __name__ == '__main__':
    enable_pretty_logging()

    loop = IOLoop.current()
    loop.add_callback(run_subproc)
    loop.start()