Python OS polling select - python-3.x

Question

I am following the David Beazley Python Concurrency From the Ground Up: LIVE! - PyCon 2015 talk where I aim to understand basics of Python concurrency.
I would like to know why Python select is failing which is used for polling the operating system (OS) and check if there is some task that needs to be done.
from socket import *
from select import select
from collections import deque
tasks = deque()
recv_wait = {}
send_wait = {}
def fib(n):
if n <= 2:
return 1
else:
return fib(n-1)+fib(n-2)
def run():
while any([tasks, recv_wait, send_wait]):
while not tasks:
can_recv, can_send, _ = select(recv_wait, send_wait, [])
for s in can_recv:
tasks.append(recv_wait.pop(s))
for s in can_send:
tasks.append(send_wait.pop(s))
task = tasks.popleft()
try:
why, what = next(task)
if why == 'recv':
recv_wait[what] = task
elif why == 'send':
send_wait[what] = task
else:
raise RuntimeError("Arg!!")
except StopIteration:
print("task done")
def fib_server(address):
sock = socket(AF_INET, SOCK_STREAM)
sock.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
sock.bind(address)
sock.listen(5)
while True:
yield 'recv', sock
client, addr = sock.accept()
print("Connection", addr)
tasks.append(fib_handler(client))
def fib_handler(client):
while True:
yield 'recv', client
req = client.recv(100)
if not req:
break
n = int(req)
result = fib(n)
result = fib(n)
resp = str(result).encode('ascii') + b'\n'
yield 'send',resp
client.send(resp)
print("Closed")
tasks.append(fib_server(('', 25000)))
run()
# Separate terminal window
nc localhost 25000
12
# Running Python server
➜ python3 -i aserver.py
Connection ('127.0.0.1', 61098)
Traceback (most recent call last):
File "aserver.py", line 63, in <module>
run()
File "aserver.py", line 20, in run
can_recv, can_send, _ = select(recv_wait, send_wait,[])
TypeError: argument must be an int, or have a fileno() method.

Answer 1

def fib_handler(client):
while True:
yield 'recv', client
req = client.recv(100)
if not req:
break
n = int(req)
result = fib(n)
result = fib(n) # duplicate
resp = str(result).encode('ascii')+ b'\n'
yield 'send',resp # should be yielding fd (client)
client.send(resp)
print("Closed")