Qfyilyi

while i'm testing sockets in python ,i'm wondering why does it takes such long time to complete a UDP send & receive process.
(it takes about 2ms per contact LOCALLY with my code ,it's just too slow to use it communicating between processes or threads)

Am I doing some thing wrong ?(run in single thread or something?) Or it's because python is just that slow ?

Server demo code like this :

import socket,time



s = socket.socket(socket.AF_INET,socket.SOCK_DGRAM)

s.bind('localhost',6000)



while True:

    data, addr = s.recvfrom(1024)

    s.sendto(b'',addr)

And client is like this:

import socket,time



s = socket.socket(socket.AF_INET,socket.SOCK_DGRAM)



for i in range(100):

    t = time.time()

    s.sendto('localhost',6000)

    s.recv(1024)

    print(time.time() - t)

the output is like this:

0.00799250602722168

0.0020029544830322266

0.0010268688201904297

0.0010089874267578125

0.0010042190551757812

0.0020051002502441406

0.002005338668823242

0.002005338668823242

0.002005338668823242

0.002005338668823242

0.002005338668823242

0.002005338668823242

0.0020051002502441406

0.0020058155059814453

0.0027120113372802734

0.0010039806365966797

0.0020055770874023438

0.00200653076171875

0.002003908157348633

0.0010035037994384766

0.0020051002502441406

0.0020074844360351562

0.0010325908660888672

0.002005338668823242

0.002690553665161133

0.0010037422180175781

0.0020055770874023438

0.0020051002502441406

0.002005338668823242

0.002005338668823242

0.001806020736694336

0.0010192394256591797

0.0010271072387695312

0.0020055770874023438

0.002007007598876953

0.0020041465759277344

0.002004861831665039

0.001999378204345703

0.0020067691802978516

0.0019817352294921875

0.002007007598876953

Can anybody solve my problem?
thanks a lot

I get about two orders of magnitude faster than that (~0.01ms, 3.4GHz i7-6700) maybe localhost resolves somewhere strange and it needs to retry things?

your code also doesn't work for me, am posting the code I used. server side first:

import socket



with socket.socket(socket.AF_INET, socket.SOCK_DGRAM) as s:

  s.bind(('localhost',6000))

  while True:

    data, addr = s.recvfrom(1024)

    s.sendto(b'',addr)

now client side:

import socket

from time import time



addr = socket.getaddrinfo(

  'localhost', 6000,

  socket.AF_INET, socket.SOCK_DGRAM)[0]



with socket.socket(*addr[:3]) as s:

  s.connect(addr[4])

  for i in range(1000):

    t1 = time()

    s.send(b'')

    t2 = time()

    s.recv(1024)

    t3 = time()

    if i % 100 == 0:

      print('{:.3f}ms {:.3f}ms'.format((t2 - t1) * 1000, (t3 - t2) * 1000))

note that I use socket.connect() to try and cut down on resolution time, but this doesn't seem to make any difference for me. I get:

0.218ms 0.006ms

0.004ms 0.010ms

0.004ms 0.007ms

0.004ms 0.008ms

0.004ms 0.011ms

0.004ms 0.010ms

0.004ms 0.010ms

0.004ms 0.009ms

0.004ms 0.010ms

0.004ms 0.008ms

back, i.e. first time around is slow, then it's quick

unix domain sockets might be faster if you care less about portability, otherwise you could try zeromq which has nice Python packages