Creating non-blocking socket in python
17,807
Solution 1
setblocking
only affects the socket you use it on. So you have to add conn.setblocking(0)
to see an effect: The recv
will then return immediately if there is no data available.
Solution 2
You just need to call setblocking(0)
on the connected socket, i.e. conn
.
import socket
s = socket.socket()
s.bind(('127.0.0.1', 12345))
s.listen(5)
s.setblocking(0)
>>> conn, addr = s.accept()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib64/python2.7/socket.py", line 202, in accept
sock, addr = self._sock.accept()
socket.error: [Errno 11] Resource temporarily unavailable
# start your client...
>>> conn, addr = s.accept()
>>> conn.recv() # this will hang until the client sends some data....
'hi there\n'
>>> conn.setblocking(0) # set non-blocking on the connected socket "conn"
>>> conn.recv()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
socket.error: [Errno 11] Resource temporarily unavailable
Author by
Gray
Updated on June 13, 2022Comments
-
Gray almost 2 years
I was trying to understand how non-blocking sockets work ,so I wrote this simple server in python .
import socket s=socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.bind(('127.0.0.1',1000)) s.listen(5) s.setblocking(0) while True: try: conn, addr = s.accept() print ('connection from',addr) data=conn.recv(100) print ('recived: ',data,len(data)) except: pass
Then I tried to connect to this server from multiple instances of this client
import socket s=socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect(('127.0.0.1',1000)) while True: continue
But for some reason putting blocking to 0 or 1 dose not seem to have an effect and server's recv method always block the execution. So, dose creating non-blocking socket in python require more than just setting the blocking flag to 0.