sample to run subprocess and log stdout/stderr with asyncio

exec.py

__author__ = 'leonmax'

import asyncio
from asyncio import (coroutine, subprocess)
import sys
import logging

FORMAT = '%(asctime)s - %(name)s - %(levelname)s - %(message)s'
logging.basicConfig(level=logging.INFO, format=FORMAT)

@coroutine
def log_stream(level, stream):
    while not stream.at_eof():
        data = yield from stream.readline()
        line = data.decode('ascii').rstrip()
        logging.log(level, line)

@coroutine
def execute(command, *argument):
    proc = yield from asyncio.create_subprocess_exec(command, *argument,
                                                     stdout=subprocess.PIPE,
                                                     stderr=subprocess.PIPE)
    tasks = [asyncio.async(log_stream(logging.INFO, proc.stdout)),
             asyncio.async(log_stream(logging.ERROR, proc.stderr)),
             asyncio.async(proc.wait())]
    yield from asyncio.wait(tasks)

if __name__ == "__main__":
    loop = asyncio.get_event_loop()
    loop.run_until_complete(execute(sys.executable, *sys.argv[1:]))
    loop.close()

sample.md

run subproc.py from exec.py and capture its stdout/stderr, good for writing a wrapper script

just run the following:

python exec.py subproc.py 10

subproc.py

__author__ = 'leonmax'

from asyncio import coroutine, sleep, get_event_loop
import sys

@coroutine
def run(times):
    for i in range(times):
        print("trust me ", i)
        yield from sleep(1)
        print("I blew it", file=sys.stderr)
        yield from sleep(1)

if __name__ == "__main__":
    loop = get_event_loop()
    times = int(sys.argv[1]) if len(sys.argv) > 1 else 10
    loop.run_until_complete(run(times))
    loop.close()