The solution I've come up with so far uses SubprocessProtocol to receive output from the child process, and the associated transport to get the process' exit code. I don't know if this is optimal though. I've based my approach on an answer to a similar question by J.F. Sebastian.
import asyncio
import contextlib
import os
import locale
class SubprocessProtocol(asyncio.SubprocessProtocol):
def pipe_data_received(self, fd, data):
if fd == 1:
name = 'stdout'
elif fd == 2:
name = 'stderr'
text = data.decode(locale.getpreferredencoding(False))
print('Received from {}: {}'.format(name, text.strip()))
def process_exited(self):
loop.stop()
if os.name == 'nt':
# On Windows, the ProactorEventLoop is necessary to listen on pipes
loop = asyncio.ProactorEventLoop()
asyncio.set_event_loop(loop)
else:
loop = asyncio.get_event_loop()
with contextlib.closing(loop):
# This will only connect to the process
transport = loop.run_until_complete(loop.subprocess_exec(
SubprocessProtocol, 'python', '-c', 'print('Hello async world!')'))[0]
# Wait until process has finished
loop.run_forever()
print('Program exited with: {}'.format(transport.get_returncode()))
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