Multithreaded web server in python

Question

I'm trying to create multithreaded web server in python, but it only responds to one request at a time and I can't figure out why. Can you help me, please?

#!/usr/bin/env python2
# -*- coding: utf-8 -*-

from SocketServer import ThreadingMixIn
from  BaseHTTPServer import HTTPServer
from SimpleHTTPServer import SimpleHTTPRequestHandler
from time import sleep

class ThreadingServer(ThreadingMixIn, HTTPServer):
    pass

class RequestHandler(SimpleHTTPRequestHandler):
    def do_GET(self):
        self.send_response(200)
        self.send_header('Content-type', 'text/plain')
        sleep(5)
        response = 'Slept for 5 seconds..'
        self.send_header('Content-length', len(response))
        self.end_headers()
        self.wfile.write(response)

ThreadingServer(('', 8000), RequestHandler).serve_forever()

Answer 1

In python3, you can use the code below (https or http):

from http.server import HTTPServer, BaseHTTPRequestHandler
from socketserver import ThreadingMixIn
import threading

USE_HTTPS = True

class Handler(BaseHTTPRequestHandler):

    def do_GET(self):
        self.send_response(200)
        self.end_headers()
        self.wfile.write(b'Hello world\t' + threading.currentThread().getName().encode() + b'\t' + str(threading.active_count()).encode() + b'\n')


class ThreadingSimpleServer(ThreadingMixIn, HTTPServer):
    pass

def run():
    server = ThreadingSimpleServer(('0.0.0.0', 4444), Handler)
    if USE_HTTPS:
        import ssl
        server.socket = ssl.wrap_socket(server.socket, keyfile='./key.pem', certfile='./cert.pem', server_side=True)
    server.serve_forever()


if __name__ == '__main__':
    run()

You will figure out this code will create a new thread to deal with every request.

Command below to generate self-sign certificate:

openssl req -x509 -newkey rsa:4096 -nodes -out cert.pem -keyout key.pem -days 365

If you are using Flask, this blog is great.

Answer 2

Here is another good example of a multithreaded SimpleHTTPServer-like HTTP server: MultithreadedSimpleHTTPServer on GitHub.

Answer 3

Check this post from Doug Hellmann's blog.

from BaseHTTPServer import HTTPServer, BaseHTTPRequestHandler
from SocketServer import ThreadingMixIn
import threading

class Handler(BaseHTTPRequestHandler):

    def do_GET(self):
        self.send_response(200)
        self.end_headers()
        message =  threading.currentThread().getName()
        self.wfile.write(message)
        self.wfile.write('\n')
        return

class ThreadedHTTPServer(ThreadingMixIn, HTTPServer):
    """Handle requests in a separate thread."""

if __name__ == '__main__':
    server = ThreadedHTTPServer(('localhost', 8080), Handler)
    print 'Starting server, use <Ctrl-C> to stop'
    server.serve_forever()

Answer 4

I have developed a PIP Utility called ComplexHTTPServer that is a multi-threaded version of SimpleHTTPServer.

To install it, all you need to do is:

pip install ComplexHTTPServer

Using it is as simple as:

python -m ComplexHTTPServer [PORT]

(By default, the port is 8000.)

Answer 5

It's amazing how many votes these solutions that break streaming are getting. If streaming might be needed down the road, then ThreadingMixIn and gunicorn are no good because they just collect up the response and write it as a unit at the end (which actually does nothing if your stream is infinite).

Your basic approach of combining BaseHTTPServer with threads is fine. But the default BaseHTTPServer settings re-bind a new socket on every listener, which won't work in Linux if all the listeners are on the same port. Change those settings before the serve_forever() call. (Just like you have to set self.daemon = True on a thread to stop ctrl-C from being disabled.)

The following example launches 100 handler threads on the same port, with each handler started through BaseHTTPServer.

import time, threading, socket, SocketServer, BaseHTTPServer

class Handler(BaseHTTPServer.BaseHTTPRequestHandler):

    def do_GET(self):
        if self.path != '/':
            self.send_error(404, "Object not found")
            return
        self.send_response(200)
        self.send_header('Content-type', 'text/html; charset=utf-8')
        self.end_headers()

        # serve up an infinite stream
        i = 0
        while True:
            self.wfile.write("%i " % i)
            time.sleep(0.1)
            i += 1

# Create ONE socket.
addr = ('', 8000)
sock = socket.socket (socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.bind(addr)
sock.listen(5)

# Launch 100 listener threads.
class Thread(threading.Thread):
    def __init__(self, i):
        threading.Thread.__init__(self)
        self.i = i
        self.daemon = True
        self.start()
    def run(self):
        httpd = BaseHTTPServer.HTTPServer(addr, Handler, False)

        # Prevent the HTTP server from re-binding every handler.
        # https://stackoverflow.com/questions/46210672/
        httpd.socket = sock
        httpd.server_bind = self.server_close = lambda self: None

        httpd.serve_forever()
[Thread(i) for i in range(100)]
time.sleep(9e9)