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Why can't I access a specific variable inside of a threaded class

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Haley Mueller wants to draw more attention to this question.
I'm new to Python so this could be a simple fix.
I am using Flask and sockets for this Python project. I am starting the socket on another thread so I can actively listen for new messages. I have an array variable called 'SocketConnections' that is within my UdpComms class. The variable gets a new 'Connection' appended to it when a new socket connection is made. That works correctly. My issue is that when I try to read 'SocketConnections' from outside of the thread looking in, it is an empty array.
server.py
from flask import Flask, jsonify
import UdpComms as U
app = Flask(__name__)
#app.route('/api/talk', methods=['POST'])
def talk():
global global_server_socket
apples = global_server_socket.SocketConnections
return jsonify(message=apples)
global_server_socket = None
def start_server():
global global_server_socket
sock = U.UdpComms(udpIP="127.0.0.1", portTX=8000, portRX=8001, enableRX=True, suppressWarnings=True)
i = 0
global_server_socket = sock
while True:
i += 1
data = sock.ReadReceivedData() # read data
if data != None: # if NEW data has been received since last ReadReceivedData function call
print(data) # print new received data
time.sleep(1)
if __name__ == '__main__':
server_thread = threading.Thread(target=start_server)
server_thread.start()
app.run(debug=True,host='192.168.0.25')
UdpComms.py
import json
import uuid
class UdpComms():
def __init__(self,udpIP,portTX,portRX,enableRX=False,suppressWarnings=True):
self.SocketConnections = []
import socket
self.udpIP = udpIP
self.udpSendPort = portTX
self.udpRcvPort = portRX
self.enableRX = enableRX
self.suppressWarnings = suppressWarnings # when true warnings are suppressed
self.isDataReceived = False
self.dataRX = None
# Connect via UDP
self.udpSock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) # internet protocol, udp (DGRAM) socket
self.udpSock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) # allows the address/port to be reused immediately instead of it being stuck in the TIME_WAIT state waiting for late packets to arrive.
self.udpSock.bind((udpIP, portRX))
# Create Receiving thread if required
if enableRX:
import threading
self.rxThread = threading.Thread(target=self.ReadUdpThreadFunc, daemon=True)
self.rxThread.start()
def __del__(self):
self.CloseSocket()
def CloseSocket(self):
# Function to close socket
self.udpSock.close()
def SendData(self, strToSend):
# Use this function to send string to C#
self.udpSock.sendto(bytes(strToSend,'utf-8'), (self.udpIP, self.udpSendPort))
def SendDataAddress(self, strToSend, guid):
# Use this function to send string to C#
print('finding connection: ' + guid)
if self.SocketConnections:
connection = self.GetConnectionByGUID(guid)
print('found connection: ' + guid)
if connection is not None:
self.udpSock.sendto(bytes(strToSend,'utf-8'), connection.Address)
def ReceiveData(self):
if not self.enableRX: # if RX is not enabled, raise error
raise ValueError("Attempting to receive data without enabling this setting. Ensure this is enabled from the constructor")
data = None
try:
data, _ = self.udpSock.recvfrom(1024)
print('Socket data recieved from: ', _)
if self.IsNewConnection(_) == True:
print('New socket')
self.SendDataAddress("INIT:" + self.SocketConnections[-1].GUID, self.SocketConnections[-1].GUID)
data = data.decode('utf-8')
except WindowsError as e:
if e.winerror == 10054: # An error occurs if you try to receive before connecting to other application
if not self.suppressWarnings:
print("Are You connected to the other application? Connect to it!")
else:
pass
else:
raise ValueError("Unexpected Error. Are you sure that the received data can be converted to a string")
return data
def ReadUdpThreadFunc(self): # Should be called from thread
self.isDataReceived = False # Initially nothing received
while True:
data = self.ReceiveData() # Blocks (in thread) until data is returned (OR MAYBE UNTIL SOME TIMEOUT AS WELL)
self.dataRX = data # Populate AFTER new data is received
self.isDataReceived = True
# When it reaches here, data received is available
def ReadReceivedData(self):
data = None
if self.isDataReceived: # if data has been received
self.isDataReceived = False
data = self.dataRX
self.dataRX = None # Empty receive buffer
if data != None and data.startswith('DIALOG:'): #send it info
split = data.split(':')[1]
return data
class Connection:
def __init__(self, gUID, address) -> None:
self.GUID = gUID
self.Address = address
def IsNewConnection(self, address):
for connection in self.SocketConnections:
if connection.Address == address:
return False
print('Appending new connection...')
connection = self.Connection(str(uuid.uuid4()),address)
self.SocketConnections.append(connection)
return True
def GetConnectionByGUID(self, guid):
for connection in self.SocketConnections:
if connection.GUID == guid:
return connection
return None
As mentioned above. When IsNewConnection() is called in UdpComms it does append a new object to SocketConnections. It's just trying to view the SocketConnections in the app.route that is empty. My plans are to be able to send socket messages from the app.routes

For interprocess communication you may try to use something like shared memory documented here
Instead of declaring your self.SocketConnections as a list = []
you'd use self.SocketConnections = Array('i', range(10)) (you are then limited to remembering only 10 connections though).

Why won't this python socket chat server work correctly?

So I have made some code that follows. It is suppose to let a server and a client communicate... but it doesn't work.
Can someone explain why, or better yet fix my code???
Server.
import time
import socket
from threading import Thread
global sS
sS = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sS.bind(('', 2347))
sSconAddresses = []
sSconData = []
print(" Server : Running ... ")
sS.listen(10)
while True:
try:
cOn, aDr = sS.accept()
sSconAddresses.insert(0, str(aDr))
sSconData.insert(0, str(cOn))
time.sleep(0.3)
except:
time.sleep(0.1)
pass
def ConHandler():
for _ in sSconData:
PacketData = _.recv(700)
if not PacketData:
_.close()
else:
stringData = PacketData.decode('utf-8')
print(stringData)
sS.sendto(PacketData, _)
ConHandlerThread = Thread(target=ConHandler)
ConHandlerThread.daemon = True
ConHandlerThread.start()
Client.
import threading, time
import socket, sys
import os
global cS
cS = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
cS.connect(('PRIVATE', 2347))
Server = ('PRIVATE', 2347)
while True:
PacketData = input(" Client> ")
ByteData = PacketData.encode('utf-8')
cS.sendto(ByteData, Server)
It doesn't return any errors so I am confused why it doesn't work.

First of all, in your server-side code, you're having a while True before starting your thread, so it can't work.
Then, if you succeed starting your thread by moving the code, its for will see an empty list, so it will not loop, and just exit right here.
Starting from your code, here's something that works:
The client:
import socket
def main():
client_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
client_socket.connect(('127.0.0.1', 2345))
while True:
packetdata = input(" Client> ")
bytedata = packetdata.encode()
client_socket.send(bytedata)
print(client_socket.recv(700).decode())
if __name__ == '__main__':
main()
The server:
import socket
from threading import Thread
from queue import Queue
def client_handler(client_socket):
while True:
data = client_socket.recv(700)
print(data)
client_socket.send("Server {}".format(data.decode()).encode())
def conn_handler(conn_queue):
while True:
conn, address = conn_queue.get()
print("Handler getting a connection from {}".format(address))
client_thread = Thread(target=client_handler, args=(conn,))
client_thread.daemon = True
client_thread.start()
def main():
print("Server: Running ...")
conn_queue = Queue()
server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
server_socket.bind(('', 2345))
server_socket.listen(10)
con_handler_thread = Thread(target=conn_handler, args=(conn_queue,))
con_handler_thread.daemon = True
con_handler_thread.start()
while True:
conn_queue.put(server_socket.accept())
if __name__ == '__main__':
main()
Note that this is suboptimal, starting one thread per client is not the way to go. The best way to handle this kind of situation is to keep everything in a single thread and use a select-like function to know what to do. However select is a bit limited too (like 1024 connections max, hardcoded in the libc), so the way to go is to use epoll / kqueue / whatever better than poll / select, and there's a module for this: https://docs.python.org/3/library/select.html
Yet using the select module is still the old, manual, cubersome way to express your needs, you should take a look at the coroutine based API of asyncio which enable a clear way to express the intention.
The asyncio equivalent may look like:
import asyncio
async def client():
reader, writer = await asyncio.open_connection('127.0.0.1', 8888)
while True:
message = input("Client> ")
writer.write(message.encode())
data = await reader.read(100)
print('Received: {}'.format(data.decode()))
loop = asyncio.get_event_loop()
loop.run_until_complete(client())
And, server side:
import asyncio
async def handle_client(reader, writer):
while True:
data = await reader.read(100)
if not data:
return
message = data.decode()
addr = writer.get_extra_info('peername')
print("Received %r from %r" % (message, addr))
print("Send: %r" % message)
writer.write(data)
await writer.drain()
loop = asyncio.get_event_loop()
coro = asyncio.start_server(handle_client, '127.0.0.1', 8888)
server = loop.run_until_complete(coro)
print('Serving on {}'.format(server.sockets[0].getsockname()))
loop.run_forever()

Zeromq (pyzmq) ROUTER procession of multiple clients' data and subsequent timeout handling

I have a ROUTER whose purpose is to accumulate image data from multiple DEALER clients and perform OCR on the complete image. I found that the most efficient way of handling the OCR is through the utilization of Python's multiprocessing library; the accumulated image bytes are put into a Queue for due procession in a separate Process. However, I need to ensure that when a client experiences a timeout that the Process is properly terminated and doesn't meaninglessly linger and hog resources.
In my current solution I insert each newly-connected client into a dict where the value is my ClientHandler class that possesses all image data and spawns a Thread that sets a boolean variable named "timeout" to True when 5 seconds have elapsed. Should a new message be received within that 5 second frame, bump is called & the timer is reset back to 0, otherwise I cleanup prior to thread termination and the reference is deleted from the dict in the main loop:
import threading
import time
import zmq
class ClientHandler(threading.Thread):
def __init__(self, socket):
self.elapsed = time.time()
self.timeout = False
self.socket = socket
super(ClientHandler, self).__init__()
def run(self):
while time.time() - self.elapsed < 5.0:
pass
self.timeout = True
# CLIENT TIMED OUT
# HANDLE TERMINATION AND CLEAN UP HERE
def bump(self):
self.elapsed = time.time()
def handle(self, id, header, data):
# HANDLE CLIENT DATA HERE
# ACCUMULATE IMAGE BYTES, ETC
self.socket.send_multipart([id, str(0)])
def server_task():
clients = dict()
context = zmq.Context.instance()
server = context.socket(zmq.ROUTER)
server.setsockopt(zmq.RCVTIMEO, 0)
server.bind("tcp://127.0.0.1:7777")
while True:
try:
id, header, data = server.recv_multipart()
client = clients.get(id)
if client == None:
client = clients[id] = ClientHandler(server)
client.start()
client.bump()
client.handle(id, header, data)
except zmq.Again:
for id in clients.keys():
if clients[id].timeout:
del clients[id]
context.term()
if __name__ == "__main__":
server_task()
But this entire method just doesn't feel right. Am I going about this improperly? If so, I would greatly appreciate if someone could point me in the right direction.

Figured it out myself, hoping it may be of assistance to others.
I instead have a ROUTER on an assigned port that distributes unique ports to each client, which thereafter connects to the newly-bound socket on said unique port. When a client disconnects, the port is recycled for reassignment.
import sys
import zmq
from multiprocessing import Process, Queue, Value
def server_task():
context = zmq.Context.instance()
server = context.socket(zmq.ROUTER)
server.bind("tcp://127.0.0.1:7777")
timeout_queue = Queue()
port_list = [ 1 ]
proc_list = [ ]
while True:
try:
id = server.recv_multipart()[0]
# Get an unused port from the list
# Ports from clients that have timed out are recycled here
while not timeout_queue.empty():
port_list.append(timeout_queue.get())
port = port_list.pop()
if len(port_list) == 0:
port_list.append(port + 1)
# Spawn a new worker task, binding the port to a socket
proc_running = Value("b", True)
proc_list.append(proc_running)
Process(target=worker_task, args=(proc_running, port, timeout_queue)).start()
# Send the new port to the client
server.send_multipart([id, str(7777 + port)])
except KeyboardInterrupt:
break
# Safely allow our worker processes to terminate
for proc_running in proc_list:
proc_running.value = False
context.term()
def worker_task(proc_running, port, timeout_queue):
context = zmq.Context.instance()
worker = context.socket(zmq.ROUTER)
worker.setsockopt(zmq.RCVTIMEO, 5000)
worker.bind("tcp://127.0.0.1:%d" % (7777 + port, ))
while proc_running.value:
try:
id, data = worker.recv_multipart()
worker.send_multipart([id, data])
except zmq.Again:
timeout_queue.put(port)
context.term()
break
print("Client on port %d disconnected" % (7777 + port, ))

Making a Fast Port Scanner

So I'm making a port scanner in python...
import socket
ip = "External IP"
s = socket.socket(2, 1) #socket.AF_INET, socket.SOCK_STREAM
def porttry(ip, port):
try:
s.connect((ip, port))
return True
except:
return None
for port in range(0, 10000):
value = porttry(ip, port)
if value == None:
print("Port not opened on %d" % port)
else:
print("Port opened on %d" % port)
break
raw_input()
But this is too slow, I want to somehow be able to some how close or break code after a period of time of not returning anything.

In addition to setting socket timeout, you can also apply multi-threading technique to turbo boost the process. It will be, at best, N times faster when you have N ports to scan.
# This script runs on Python 3
import socket, threading
def TCP_connect(ip, port_number, delay, output):
TCPsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
TCPsock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
TCPsock.settimeout(delay)
try:
TCPsock.connect((ip, port_number))
output[port_number] = 'Listening'
except:
output[port_number] = ''
def scan_ports(host_ip, delay):
threads = [] # To run TCP_connect concurrently
output = {} # For printing purposes
# Spawning threads to scan ports
for i in range(10000):
t = threading.Thread(target=TCP_connect, args=(host_ip, i, delay, output))
threads.append(t)
# Starting threads
for i in range(10000):
threads[i].start()
# Locking the main thread until all threads complete
for i in range(10000):
threads[i].join()
# Printing listening ports from small to large
for i in range(10000):
if output[i] == 'Listening':
print(str(i) + ': ' + output[i])
def main():
host_ip = input("Enter host IP: ")
delay = int(input("How many seconds the socket is going to wait until timeout: "))
scan_ports(host_ip, delay)
if __name__ == "__main__":
main()

here is a quick and simple port scanner, it scans 100000 ports in 180 sec:
import threading
import socket
target = 'pythonprogramming.net'
#ip = socket.gethostbyname(target)
def portscan(port):
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.settimeout(0.5)#
try:
con = s.connect((target,port))
print('Port :',port,"is open.")
con.close()
except:
pass
r = 1
for x in range(1,100):
t = threading.Thread(target=portscan,kwargs={'port':r})
r += 1
t.start()

Consider setting a timeout instead of a for loop by using socket.setdefaulttimeout(timeout).

This should be a bit faster.
#-*-coding:utf8;-*-
#qpy:3
#qpy:console
import socket
import os
# This is used to set a default timeout on socket
# objects.
DEFAULT_TIMEOUT = 0.5
# This is used for checking if a call to socket.connect_ex
# was successful.
SUCCESS = 0
def check_port(*host_port, timeout=DEFAULT_TIMEOUT):
''' Try to connect to a specified host on a specified port.
If the connection takes longer then the TIMEOUT we set we assume
the host is down. If the connection is a success we can safely assume
the host is up and listing on port x. If the connection fails for any
other reason we assume the host is down and the port is closed.'''
# Create and configure the socket.
sock = socket.socket()
sock.settimeout(timeout)
# the SO_REUSEADDR flag tells the kernel to reuse a local
# socket in TIME_WAIT state, without waiting for its natural
# timeout to expire.
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
# Like connect(address), but return an error indicator instead
# of raising an exception for errors returned by the C-level connect() 
# call (other problems, such as “host not found,” can still raise exceptions).
# The error indicator is 0 if the operation succeeded, otherwise the value of
# the errnovariable. This is useful to support, for example, asynchronous connects.
connected = sock.connect_ex(host_port) is SUCCESS
# Mark the socket closed.
# The underlying system resource (e.g. a file descriptor)
# is also closed when all file objects from makefile() are closed.
# Once that happens, all future operations on the socket object will fail.
# The remote end will receive no more data (after queued data is flushed).
sock.close()
# return True if port is open or False if port is closed.
return connected
con = check_port('www.google.com', 83)
print(con)

One can use threading.Thread and threading.Condition to synchronize port check and spawning new threads.
Script example usage:
python port_scan.py google.com 70 90
Checking 70 - 80
Checking 80 - 84
Checking 84 - 90
Found active port 80
Checking 90 - 91
Checking 91 - 94
All threads started ...
port_scan.py:
# import pdb
import socket, threading
from traceback import print_exc
class AllThreadsStarted(Exception): pass
class IPv4PortScanner(object):
def __init__(self, domain, timeout=2.0, port_range=(1024, 65535), threadcount=10):
self.domain = domain
self.timeout = timeout
self.port_range = port_range
self.threadcount = threadcount
self._lock = threading.Lock()
self._condition = threading.Condition(self._lock)
self._ports_active = []
self._ports_being_checked = []
self._next_port = self.port_range[0]
def check_port_(self, port):
"If connects then port is active"
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.settimeout(self.timeout)
try:
sock.connect((self.domain, port))
with self._lock:
self._ports_active.append(port)
print ("Found active port {}".format(port))
sock.close()
except socket.timeout, ex:
return
except:
print_exc()
# pdb.set_trace()
def check_port(self, port):
"updates self._ports_being_checked list on exit of this method"
try:
self.check_port_(port)
finally:
self._condition.acquire()
self._ports_being_checked.remove(port)
self._condition.notifyAll()
self._condition.release()
def start_another_thread(self):
if self._next_port > self.port_range[1]:
raise AllThreadsStarted()
port = self._next_port
self._next_port += 1
t = threading.Thread(target=self.check_port, args=(port,))
# update books
with self._lock:
self._ports_being_checked.append(port)
t.start()
def run(self):
try:
while True:
self._condition.acquire()
while len(self._ports_being_checked) >= self.threadcount:
# we wait for some threads to complete the task
self._condition.wait()
slots_available = self.threadcount - len(self._ports_being_checked)
self._condition.release()
print ("Checking {} - {}".format(self._next_port, self._next_port+slots_available))
for i in xrange(slots_available):
self.start_another_thread()
except AllThreadsStarted, ex:
print ("All threads started ...")
except:
print_exc()
if __name__ == "__main__":
import sys
domain = sys.argv[1]
port_s = int(sys.argv[2])
port_e = int(sys.argv[3])
scanner = IPv4PortScanner(domain=domain, port_range=(port_s, port_e))
scanner.run()

I think that this one snippet could help you : http://www.coderholic.com/python-port-scanner/

socket.setdefaulttimeout(0.5)
This will make the program faster!

socket.setdefualttimeout (time)
is used to keep trying to connect with port for perticular time...when you send request and there is timeout set for 2 seconds so it will try to connect with port for 2 seconds....if there will be no response from that port in 2 seconds....it will be count as a dead port

The following port scanner has a few constants defined at the top that you can modify as needed:
PURPOSE -- help message for the command line
PORTS -- range of ports you would like scanned
POOL_SIZE -- number of processes to scan with
TIMEOUT -- how long to wait for server connection
Feel free to adapt this according to your requirements. Maybe add some command line arguments?
#! /usr/bin/env python3
import argparse
import collections
import itertools
import multiprocessing
import operator
import socket
PURPOSE = 'Scan for open ports on a computer.'
PORTS = range(1 << 16)
POOL_SIZE = 1 << 8
TIMEOUT = 0.01
def main():
"""Get computer to scan, connect with process pool, and show open ports."""
parser = argparse.ArgumentParser(description=PURPOSE)
parser.add_argument('host', type=str, help='computer you want to scan')
host = parser.parse_args().host
with multiprocessing.Pool(POOL_SIZE, socket.setdefaulttimeout, [TIMEOUT]) \
as pool:
results = pool.imap_unordered(test, ((host, port) for port in PORTS))
servers = filter(operator.itemgetter(0), results)
numbers = map(operator.itemgetter(1), servers)
ordered = sorted(numbers)
print(f'Ports open on {host}:', *format_ports(ordered), sep='\n ')
field_names = 'family', 'socket_type', 'protocol', 'canon_name', 'address'
AddressInfo = collections.namedtuple('AddressInfo', field_names)
del field_names
def test(address):
"""Try connecting to the server and return whether or not it succeeded."""
host, port = address
for info in itertools.starmap(AddressInfo, socket.getaddrinfo(host, port)):
try:
probe = socket.socket(info.family, info.socket_type, info.protocol)
except OSError:
pass
else:
try:
probe.connect(info.address)
except OSError:
pass
else:
probe.shutdown(socket.SHUT_RDWR)
return True, port
finally:
probe.close()
return False, port
def format_ports(ports):
"""Convert port numbers into strings and show all associated services."""
if ports:
for port in ports:
try:
service = socket.getservbyport(port)
except OSError:
service = '?'
yield f'{port:<5} = {service}'
else:
yield 'None'
if __name__ == '__main__':
main()

I've just finished tinkering with Concurrent Futures on a port scanner and by God it's fast:
import concurrent.futures
import socket
def scan_port(domainip: str, port: int) -> tuple:
try:
# Use a faster socket implementation
s = socket.create_connection((domainip, port), timeout=0.5)
# Check if the connection was successful
if s:
return (port, "open")
else:
return (port, "closed")
except Exception as e:
print(f"Error scanning port {port}: {e}")
return (port, "error")
openports = {}
# Scan the ports in parallel using the faster scanning code
with concurrent.futures.ThreadPoolExecutor() as executor:
futures = [executor.submit(scan_port, domainip, port) for port in range(1, 1024)]
for future in concurrent.futures.as_completed(futures):
status = future.result()
if status[1] == "open":
openports[status[0]] = status[1]

Wrapping Pyro's NameServer the correct way

I'm trying to warp Pyro's name server into a more convenient object that would allow me to start and stop it as I wish. For example, I would like to be able to do something like
nameServer = NameServer("localhost")
nameServer.startNS()
[... make some other operations...]
nameServer.stopNS()
nameServer = None
[... make some other operations...]
nameServer = NameServer("localhost")
nameServer.startNS()
using the following definition for the NameServer class:
class NameServer(threadutil.Thread):
def __init__(self, host, isDeamon=True, port=None, enableBroadcast=True,
bchost=None, bcport=None, unixsocket=None, nathost=None, natport=None):
super(NameServer,self).__init__()
self.setDaemon(isDeamon)
self.host=host
self.started=threadutil.Event()
self.unixsocket = unixsocket
self.port = port
self.enableBroadcast = enableBroadcast
self.bchost = bchost
self.bcport = bcport
self.nathost = nathost
self.natport = natport
"""
This code is taken from Pyro4.naming.startNSloop
"""
self.ns_daemon = naming.NameServerDaemon(self.host, self.port, self.unixsocket,
nathost=self.nathost, natport=self.natport)
self.uri = self.ns_daemon.uriFor(self.ns_daemon.nameserver)
internalUri = self.ns_daemon.uriFor(self.ns_daemon.nameserver, nat=False)
self.bcserver=None
if self.unixsocket:
hostip = "Unix domain socket"
else:
hostip = self.ns_daemon.sock.getsockname()[0]
if hostip.startswith("127."):
enableBroadcast=False
if enableBroadcast:
# Make sure to pass the internal uri to the broadcast responder.
# It is almost always useless to let it return the external uri,
# because external systems won't be able to talk to this thing anyway.
bcserver=naming.BroadcastServer(internalUri, self.bchost, self.bcport)
bcserver.runInThread()
def run(self):
try:
self.ns_daemon.requestLoop()
finally:
self.ns_daemon.close()
if self.bcserver is not None:
self.bcserver.close()
def startNS(self):
self.start()
def stopNS(self):
self.ns_daemon.shutdown()
if self.bcserver is not None:
self.bcserver.shutdown()
So far, so good. It works as expected. However, if I run a command Pyro4.naming.locateNS() from another thread when the name server is running, then the next time I call nameServer.stopNS(), the program freezes. Anyone has an idea why? And what would be the best (at least a better) way to write such a NameServer wrapper.

There is an example in the Pyro4 repository that you could adapt.
https://github.com/delmic/Pyro4/blob/master/examples/eventloop/server.py
from __future__ import print_function
import socket
import select
import sys
import Pyro4.core
import Pyro4.naming
if sys.version_info<(3,0):
input=raw_input
print("Make sure that you don't have a name server running already.")
servertype=input("Servertype thread/multiplex (t/m)?")
if servertype=='t':
Pyro4.config.SERVERTYPE="thread"
else:
Pyro4.config.SERVERTYPE="multiplex"
hostname=socket.gethostname()
class EmbeddedServer(object):
def multiply(self, x, y):
return x*y
print("initializing services... servertype=%s" % Pyro4.config.SERVERTYPE)
# start a name server with broadcast server as well
nameserverUri, nameserverDaemon, broadcastServer = Pyro4.naming.startNS(host=hostname)
assert broadcastServer is not None, "expect a broadcast server to be created"
print("got a Nameserver, uri=%s" % nameserverUri)
print("ns daemon location string=%s" % nameserverDaemon.locationStr)
print("ns daemon sockets=%s" % nameserverDaemon.sockets)
print("bc server socket=%s (fileno %d)" % (broadcastServer.sock, broadcastServer.fileno()))
# create a Pyro daemon
pyrodaemon=Pyro4.core.Daemon(host=hostname)
print("daemon location string=%s" % pyrodaemon.locationStr)
print("daemon sockets=%s" % pyrodaemon.sockets)
# register a server object with the daemon
serveruri=pyrodaemon.register(EmbeddedServer())
print("server uri=%s" % serveruri)
# register it with the embedded nameserver directly
nameserverDaemon.nameserver.register("example.embedded.server",serveruri)
print("")
# below is our custom event loop.
while True:
print("Waiting for events...")
# create sets of the socket objects we will be waiting on
# (a set provides fast lookup compared to a list)
nameserverSockets = set(nameserverDaemon.sockets)
pyroSockets = set(pyrodaemon.sockets)
rs=[broadcastServer] # only the broadcast server is directly usable as a select() object
rs.extend(nameserverSockets)
rs.extend(pyroSockets)
rs,_,_ = select.select(rs,[],[],3)
eventsForNameserver=[]
eventsForDaemon=[]
for s in rs:
if s is broadcastServer:
print("Broadcast server received a request")
broadcastServer.processRequest()
elif s in nameserverSockets:
eventsForNameserver.append(s)
elif s in pyroSockets:
eventsForDaemon.append(s)
if eventsForNameserver:
print("Nameserver received a request")
nameserverDaemon.events(eventsForNameserver)
if eventsForDaemon:
print("Daemon received a request")
pyrodaemon.events(eventsForDaemon)
nameserverDaemon.close()
broadcastServer.close()
pyrodaemon.close()
print("done")