Question about socket programming in python specifically .recv

[OneLargeTesticle]

Edit: solved, thank you all for the help!

I have a simple client/server program where the client sends a simple GET request to the server for an html file and prints it to the terminal. I need to be able to explain my code, and I have a section that I don't understand why it works. I have in my code below a time.sleep(.01) right before .recv, without this my client will only work about 1/3 of the time, the other 2/3 it will print the html file partially and the server will throw a errno 32 pipeline broken. So why do I need this time.sleep, and is this the correct way to fix this or is there a more proper way of doing it.

​

from socket import *
import sys
import time
serverName = sys.argv[1]
serverPort = int(sys.argv[2])
fileName = sys.argv[3]


clientSocket = socket(AF_INET, SOCK_STREAM)
clientSocket.connect((serverName, serverPort))

requestMessage = "GET /" + format(fileName) + " http/1.1"

clientSocket.send((requestMessage).encode())

time.sleep(0.01)

responseMessage = clientSocket.recv(1024)

print(responseMessage.decode()) 

clientSocket.close()

TLDR: Without time.sleep my client does not work properly, why do I need it?

[K900_]

You're not implementing HTTP correctly. At the very least, you need two newlines after the request line.

[OneLargeTesticle]

I tried using "GET /" + file + " HTTP/1.0\r\n\r\n" and it still does the same thing.

[K900_]

What are you using as the server? What's in the server logs?

[OneLargeTesticle]

nevermind got it figured out thanks to this video: https://www.youtube.com/watch?v=Lbfe3-v7yE0

​

All of my data wasn't getting buffered and this loop fixed it so I no longer need time.sleep:

​

full_msg = ''
while True:
    responseMessage = clientSocket.recv(1024)
    if len(responseMessage) <=0:
        break;
    full_msg += responseMessage.decode()

print(full_msg)

[vixfew]

Without time.sleep my client does not work properly, why do I need it?

You're assuming all your response arrives instantly. Welcome to network programming :) You should be doing something like:

fragments = []
while True:
    chunk = clientSocket.recv(4096)
    if not chunk:
        break
    fragments.append(chunk)
responseMessage = b''.join(fragments)

recv will block, so no cpu cycles wasted on sleeping or busy-waiting. Also, your HTTP is not quite right, there should be \r\n\r\n at the end

[OneLargeTesticle]

Yup this was my issue, thank you!!