Socket Programming with Multi-threading in Python

14 Jul, 2022
Prerequisite : Socket Programming in Python, Multi-threading in PythonSocket Programming-> It helps us to connect a client to a server. Client is message sender and receiver and server is just a listener that works on data sent by client.What is a Thread? A thread is a light-weight process that does not require much memory overhead, they are cheaper than processes.What is Multi-threading Socket Programming? port on your computerMultithreading is a process of executing multiple threads simultaneously in a single process.Multi-threading Modules : A _thread module & threading module is used for multi-threading in python, these modules help in synchronization and provide a lock to a thread in use.  
from _thread import *
import threading
A lock object is created by->  
print_lock = threading.Lock()
A lock has two states, “locked” or “unlocked”. It has two basic methods acquire() and release(). When the state is unlocked print_lock.acquire() is used to change state to locked and print_lock.release() is used to change state to unlock.The function thread.start_new_thread() is used to start a new thread and return its identifier. The first argument is the function to call and its second argument is a tuple containing the positional list of arguments.Let’s study client-server multithreading socket programming by code- Note:-The code works with python3. Multi-threaded Server Code  
Python3
# import socket programming libraryimport socket # import thread modulefrom _thread import *import threading print_lock = threading.Lock() # thread functiondef threaded(c):    while True:         # data received from client        data = c.recv(1024)        if not data:            print('Bye')                         # lock released on exit            print_lock.release()            break         # reverse the given string from client        data = data[::-1]         # send back reversed string to client        c.send(data)     # connection closed    c.close()  def Main():    host = ""     # reserve a port on your computer    # in our case it is 12345 but it    # can be anything    port = 12345    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)    s.bind((host, port))    print("socket binded to port", port)     # put the socket into listening mode    s.listen(5)    print("socket is listening")     # a forever loop until client wants to exit    while True:         # establish connection with client        c, addr = s.accept()         # lock acquired by client        print_lock.acquire()        print('Connected to :', addr[0], ':', addr[1])         # Start a new thread and return its identifier        start_new_thread(threaded, (c,))    s.close()  if __name__ == '__main__':    Main()
Console Window:
socket binded to port 12345
socket is listening
Connected to : 127.0.0.1 : 11600
Bye
Client Code  
Python
# Import socket moduleimport socket  def Main():    # local host IP '127.0.0.1'    host = '127.0.0.1'     # Define the port on which you want to connect    port = 12345     s = socket.socket(socket.AF_INET,socket.SOCK_STREAM)     # connect to server on local computer    s.connect((host,port))     # message you send to server    message = "shaurya says geeksforgeeks"    while True:         # message sent to server        s.send(message.encode('ascii'))         # message received from server        data = s.recv(1024)         # print the received message        # here it would be a reverse of sent message        print('Received from the server :',str(data.decode('ascii')))         # ask the client whether he wants to continue        ans = input('\nDo you want to continue(y/n) :')        if ans == 'y':            continue        else:            break    # close the connection    s.close() if __name__ == '__main__':    Main()
Console Window:
Received from the server : skeegrofskeeg syas ayruahs

Do you want to continue(y/n) :y
Received from the server : skeegrofskeeg syas ayruahs

Do you want to continue(y/n) :n

Process finished with exit code 0
Reference-> https://docs.python.org/2/library/thread.htmlThis article is contributed by SHAURYA UPPAL. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above. 
shreyashagrawal
Akanksha_Rai
varshagumber28
stevewillson
Computer Networks
Python
Computer Networks
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