CODEWITHSUNDEEP
pythonsocketsnetwork-programmingresponse-time
whats canasta
whats canasta

Reputation: 781

Can I improve my server response time?

I have the following sample code running on my server. It simply accepts connections, when it reads something it responds immediately:

import socket
import select

def main():
bind = ("0.0.0.0", 28889)
server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
server_socket.bind(bind)
server_socket.listen(50)
server_socket.setblocking(0)
server_socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)

clients = {}

epoll = select.epoll()  # @UndefinedVariable
epoll.register(server_socket.fileno(), select.EPOLLIN)  # @UndefinedVariable

while 1:
    events = epoll.poll(1)
    for (fileno, event) in events:
        if fileno == server_socket.fileno():
            sock, addr = server_socket.accept()
            sock.setblocking(0)
            sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
            fileno = sock.fileno()
            epoll.register(fileno, select.EPOLLIN)  # @UndefinedVariable
            clients[fileno] = sock

        elif event & select.EPOLLIN:  # @UndefinedVariable
            sock = clients[fileno]
            try:
                sock.recv(4096)
                sock.send("~\n")
            except socket.error:
                sock.close()
                del clients[fileno]

        elif event & select.EPOLLHUP:  # @UndefinedVariable
            sock = clients[fileno]
            sock.close()
            del clients[fileno]

if __name__ == "__main__":
main()

I have the following client code which connects to the server and times the response time 10x:

import socket
import time

def main():
sock = socket.socket()
sock.connect(("192.30.35.15", 28889))

for _ in xrange(10):
    start_time = time.time()
    sock.send("~\n")
    sock.recv(2048)
    end_time = time.time()
    print "Ping: %.5f" % (end_time-start_time)


if __name__ == "__main__":
main()

Here are the results I get from running it:

Ping: 0.09100
Ping: 0.11500
Ping: 0.87100
Ping: 0.24400
Ping: 0.49100
Ping: 1.45300
Ping: 0.74800
Ping: 1.59100
Ping: 0.43600
Ping: 0.27100

This seems pretty bad with pings jumping up to 1.5 seconds.

Here's what I get when I ping the server:

Reply from 192.30.35.15: bytes=32 time=83ms

Why is my response time so bad and is there anything I can do to improve it?

Note: This is a cheap rented server, is it the best I can expect? I don't know much about server administration, is there anything I should check?

Upvotes: 0

Views: 218

Answers (1)

xaxxon
xaxxon

Reputation: 19801

Remember, TCP requires a 3-way handshake, plus you're sending 10 round trips of data. What you've created is about the worst case in terms of latency / byte.

Check out your ICMP ping times .. then multiply that by like.. 25. I think you'll see that your application ping times are in line with what you should expect.

EDIT: actually while this is sound advice for many programs, I guess it doesn't exactly pertain to your situation. Your connect isn't within your timers. Still, you're looking at delays due to nagle algorithm, which you could potentially turn off for this specific code (but in general it's good to leave on). You still also want to look at your ICMP ping times to see what a good response time could possibly be given your network situation.

Upvotes: 1

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