[Python-Dev] Python 2.3b1 has 20% slower networking?

[Itamar Shtull-Trauring]

The "we always wrap socket objects with python class" change seems to
have slowed down networking on Linux (and presumably other platforms
where socket objects used to be unwrapped.)

Moshe Zadka ran some benchmarks on Linux (2.4.9 - a redhat machine at
work probably) with 2.2 and 2.3b1 using Demos/sockets/throughput.py.

For count of 1000:
2.3 server, 2.3 client: Throughput: 13556.811 K/sec.
2.3 server, 2.2 client: Throughput: 24917.862 K/sec.
2.2 server, 2.2 client: Throughput: 29838.491 K/sec.

10,000:
2.3 server, 2.3 client: Throughput: 35994.749 K/sec.
2.3 server, 2.2 client: Throughput: 34398.085 K/sec.
2.2 server, 2.2 client: Throughput: 49488.916 K/sec.

50,000:
2.3 server, 2.3 client: Throughput: 39002.538 K/sec.
2.3 server, 2.2 client: Throughput: 48064.785 K/sec.
2.2 server, 2.2 client: Throughput: 59799.672 K/sec.

On a 2.3a2 I have I did "socket.socket = socket._socketobject", and got
a 20% slowdown compared to 2.2 on throughput. (2.3a2 without this change
is the same speed as 2.2).

Can other people do some tests to verify these numbers?

If this slowdown is confirmed, it is really not acceptable, since the
change seems to have been made only to support making timeout sockets
slightly easier to use. Why should everyone have to pay a speed penalty
just so a minority of people can skip calling a
"socket.installtimeoutsupport()" at the beginning of their program? it's
just one line of code they'd need to add.

In real programs the speed drop would probably be much less pronounced,
although I bet this slows down e.g. Anthony Baxter's portforwarder quite
a bit. If Python 2.3 is released without fixing this Twisted will
probably monkeypatch the socket module so that we can get full
performance, since we have our own (unavoidable) layers of Python
indirection :)

-- 
Itamar Shtull-Trauring    http://itamarst.org/
http://www.zoteca.com -- Python & Twisted consulting