import asyncio

loop = asyncio.get_event_loop()
coro = asyncio.open_connection('127.0.0.1', 4001)
reader, writer = loop.run_until_complete(coro)
writer.write(b'hello')
writer.write_eof()

# bug: it just return and cannot get echo_msg
msg = loop.run_until_complete(reader.read(-1))
print(msg)

import asyncio

@asyncio.coroutine
def process_request(reader, writer):
    peername = writer.get_extra_info("peername")
    msg = yield from reader.read(-1)
    print(peername, msg)
    writer.write(msg)
    writer.write_eof()

loop = asyncio.get_event_loop()
coro = asyncio.start_server(process_request, host='127.0.0.1', port=4001)
server = loop.run_until_complete(coro)

try:
    loop.run_forever()
finally:
    loop.stop()

b'hello'

b''

msg = loop.run_until_complete(reader.read(-1))   # not work

python3.4.3