I'm trying to write a client-server program where server receives the requests for a database records, or files, and sends it back. Everything was working just fine until I used the pickle function to send data from client to server,
Exception in thread Thread-1:
Traceback (most recent call last):
File "/usr/lib/python2.7/threading.py", line 551, in __bootstrap_inner
self.run()
File "server.py", line 71, in run
data = pickle.loads(data)
File "/usr/lib/python2.7/pickle.py", line 1381, in loads
file = StringIO(str)
TypeError: expected read buffer, NoneType found
When I send data from server to client, there is no problem. I worked like this for a few weeks but when there is about 50 exceptions, the server program closes.
client.py file:
import socket
import sys
import time
import pickle
import struct
def recvall(sock, n):
# Helper function to recv n bytes or return None if EOF is hit
data = ''
while len(data) < n:
packet = sock.recv(n - len(data))
if not packet:
return None
data += packet
return data
def recv_msg(sock):
# Read message length and unpack it into an integer
raw_msglen = recvall(sock, 4)
if not raw_msglen:
return None
msglen = struct.unpack('>I', raw_msglen)[0]
# Read the message data
return recvall(sock, msglen)
def sending(msg):
host = 'localhost'
port = 50000
size = 1024
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((host,port))
lenght = len(msg)
if lenght>0:
msg = pickle.dumps(msg)
msg = struct.pack('>I', len(msg)) + msg
s.sendall(msg)
print 'sended string lenght: '+str(lenght)
else:
s.send('nothing sended')
data = recv_msg(s)
lenght2 = len(data)
print data
print 'received string lenght: '+str(lenght2)
#sys.stdout.write(data)
s.close()
while 1:
msg = raw_input('Input:')
sending(msg)
server.py:
class Client(threading.Thread):
def __init__(self,(client,address)):
threading.Thread.__init__(self)
self.client = client
self.address = address
self.size = 1024
def run(self):
running = 1
while running:
sock = self.client
data = self.recv_msg(sock)
data = pickle.loads(data)
if data:
msg = struct.pack('>I', len(data)) + data
self.client.sendall(msg)
else:
self.client.close()
running = 0
def recv_msg(self, sock):
# Read message length and unpack it into an integer
raw_msglen = self.recvall(sock, 4)
if not raw_msglen:
return None
msglen = struct.unpack('>I', raw_msglen)[0]
# Read the message data
return self.recvall(sock, msglen)
def recvall(self, sock, n):
# Helper function to recv n bytes or return None if EOF is hit
data = ''
while len(data) < n:
packet = sock.recv(n - len(data))
if not packet:
return None
data += packet
return data
In previous version I puted the pickle function from server to client, and it worked fine, no problems, but now I started to write it from the beginning to find the problem, but I didn't. The recv_msg method was found here: Python Socket Receive Large Amount of Data
