HTTP server: serves numbers in range for multi-host multi-core work distribution

range_server.py

# pylint: disable=C0103 (invalid-name)
"""
python range_server.py port start stop
"""
from socketserver import TCPServer
from http.server import SimpleHTTPRequestHandler
from threading import Thread
from timeit import default_timer
from time import strftime, gmtime
from sys import argv, stdout

port, start, stop = [int(a) for a in argv[1:]]
shutdown, nworkers, dt = [None, 0, 0]


class MyHttpRequestHandler(SimpleHTTPRequestHandler):
    """silence pylint"""

    def do_GET(self):
        global start, nworkers, dt  # pylint: disable=W0603 (global-statement)
        b = b""
        if len(self.path) == 1:
            nworkers += 1
            if nworkers == 1:
                dt = default_timer()
            print(nworkers, "workers active")
            stdout.flush()
        else:
            assert nworkers > 0
            if self.path[1].isdigit():
                print(self.path[1:])
                stdout.flush()
            if start < stop:
                b = bytes(str(start), "utf-8")
                start += 1
            else:
                nworkers -= 1
                if nworkers == 0:
                    dt = default_timer() - dt
                    Thread(target=shutdown, daemon=True).start()
                else:
                    print(nworkers, "workers remain")
                    stdout.flush()
        self.send_response(200)
        self.send_header("Content-length", len(b))
        self.end_headers()
        self.wfile.write(b)


def tstr(s):
    """format seconds"""
    i = round(s)
    if i >= 366 * 24 * 3600:
        return ""
    fmt = ""
    if i >= 24 * 3600:
        fmt = "%-jd "
        i -= 24 * 3600
    return "[" + strftime(fmt + "%H:%M:%S", gmtime(i)) + "]"


with TCPServer(("", port), MyHttpRequestHandler) as httpd:
    shutdown = httpd.shutdown
    httpd.serve_forever()
    print(round(dt), "seconds", tstr(dt))

pi@raspberrypi4B2:~ $ black range_server.py
All done! ✨ 🍰 ✨
1 file left unchanged.
pi@raspberrypi4B2:~ $ pylint range_server.py 

--------------------------------------------------------------------
Your code has been rated at 10.00/10 (previous run: 10.00/10, +0.00)

pi@raspberrypi4B2:~ $ 

Works with range_client script, that is started after server:

hermann@7600x:~$ ./range_client raspberrypi4B2 9000 12
hermann@7600x:~$ 

range_server.py reports 2 found Cullen primes in range(4700, 5800):

pi@raspberrypi4B2:~ $ python range_server.py 9000 4700 5800 2>err | tee out
1 workers active
2 workers active
3 workers active
4 workers active
5 workers active
6 workers active
7 workers active
4713
8 workers active
9 workers active
10 workers active
11 workers active
12 workers active
11 workers remain
10 workers remain
9 workers remain
8 workers remain
7 workers remain
6 workers remain
5 workers remain
4 workers remain
3 workers remain
2 workers remain
5795
1 workers remain
2 seconds [00:00:02]
pi@raspberrypi4B2:~ $