Skip to content

Instantly share code, notes, and snippets.

@jacobian
Created October 6, 2009 22:39
Show Gist options
  • Star 9 You must be signed in to star a gist
  • Fork 6 You must be signed in to fork a gist
  • Save jacobian/203520 to your computer and use it in GitHub Desktop.
Save jacobian/203520 to your computer and use it in GitHub Desktop.
Simple preforking echo server in Python.
"""
Simple preforking echo server in Python.
Python port of http://tomayko.com/writings/unicorn-is-unix.
"""
import os
import sys
import socket
# Create a socket, bind it to localhost:4242, and start
# listening. Runs once in the parent; all forked children
# inherit the socket's file descriptor.
acceptor = socket.socket()
acceptor.bind(('localhost', 4242))
acceptor.listen(10)
# Ryan's Ruby code here traps EXIT and closes the socket. This
# isn't required in Python; the socket will be closed when the
# socket object gets garbage collected.
# Fork you some child processes. In the parent, the call to
# fork returns immediately with the pid of the child process;
# fork never returns in the child because we exit at the end
# of the block.
for i in range(3):
pid = os.fork()
# os.fork() returns 0 in the child process and the child's
# process id in the parent. So if pid == 0 then we're in
# the child process.
if pid == 0:
# now we're in the child process; trap (Ctrl-C)
# interrupts by catching KeyboardInterrupt) and exit
# immediately instead of dumping stack to stderr.
childpid = os.getpid()
print "Child %s listening on localhost:4242" % childpid
try:
while 1:
# This is where the magic happens. accept(2)
# blocks until a new connection is ready to be
# dequeued.
conn, addr = acceptor.accept()
# For easier use, turn the socket connection
# into a file-like object.
flo = conn.makefile()
flo.write('Child %s echo> ' % childpid)
flo.flush()
message = flo.readline()
flo.write(message)
conn.close()
print "Child %s echo'd: %r" % \
(childpid, message.strip())
except KeyboardInterrupt:
sys.exit()
# Sit back and wait for all child processes to exit.
#
# Trap interrupts, write a note, and exit immediately in
# parent. This trap is not inherited by the forks because it
# runs after forking has commenced.
try:
os.waitpid(-1, 0)
except KeyboardInterrupt:
print "\nbailing"
sys.exit()
@medecau
Copy link

medecau commented Apr 1, 2010

acceptor.close()
before sys.exit() on line 67 is advised.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment