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###########################################################################
# Concurrent server - webserver3g.py #
# #
# Tested with Python 2.7.9 & Python 3.4 on Ubuntu 14.04 & Mac OS X #
# #
# - Handle zombies by establishing a signal handler and #
# calling 'waitpid' in a loop #
# - No more Zombies, this time for real #
# * use $ python client3.py --max-conns 128 to simulate the behavior #
# #
###########################################################################
import errno
import os
import signal
import socket
SERVER_ADDRESS = (HOST, PORT) = '', 8888
REQUEST_QUEUE_SIZE = 1024
def grim_reaper(signum, frame):
while True:
try:
pid, status = os.waitpid(
-1, # Wait for any child process
os.WNOHANG # Do not block and return EWOULDBLOCK error
)
except OSError:
return
if pid == 0: # no more zombies
return
def handle_request(client_connection):
request = client_connection.recv(1024)
print(request.decode())
http_response = b"""\
HTTP/1.1 200 OK
Hello, World!
"""
client_connection.sendall(http_response)
def serve_forever():
listen_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
listen_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
listen_socket.bind(SERVER_ADDRESS)
listen_socket.listen(REQUEST_QUEUE_SIZE)
print('Serving HTTP on port {port} ...'.format(port=PORT))
signal.signal(signal.SIGCHLD, grim_reaper)
while True:
try:
client_connection, client_address = listen_socket.accept()
except IOError as e:
code, msg = e.args
# restart 'accept' if it was interrupted
if code == errno.EINTR:
continue
else:
raise
pid = os.fork()
if pid == 0: # child
listen_socket.close() # close child copy
handle_request(client_connection)
client_connection.close()
os._exit(0)
else: # parent
client_connection.close() # close parent copy and loop over
if __name__ == '__main__':
serve_forever()