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benjamin-hodgson / asynqp

An AMQP library for asyncio
MIT License
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Not using TCP_NODELAY reduce performance considerably #40

Closed socketpair closed 9 years ago

socketpair commented 9 years ago

connection = yield from asynqp.connect()

give RTT 0.04 sec (!) (i.e. 22 msg send/recv ops/sec)

sock = socket.socket()
sock.connect(('localhost', 5672))
sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
connection = yield from asynqp.connect(sock=sock)

give RTT 0.004 (i.e. 234 msg send/recv ops/sec)

RPC libraries should DIFINITELY set TCP_NODELAY on sockets.

socketpair commented 9 years ago

Will profile why only ~200 ops per second. this is too small, even for so-slow-python.

socketpair commented 9 years ago

investigation show that at least OrderedDict is slow. why it ever used? can it be eliminated?

socketpair commented 9 years ago

Python in general should give about 3K/sec.... rabbitmq give nearly 50K/sec https://www.rabbitmq.com/blog/2012/04/25/rabbitmq-performance-measurements-part-2/ http://jessearmand.com/blog/2013/06/11/im-sold-with-golang/ (I have re-checked these tests on my PC)

I can attach my RPC server and client sources written using your library. Can you help me to profile ? don't know who is slowing down. library or my code. or even broker....

benjamin-hodgson commented 9 years ago

So your proposal is to modify connect so it sets TCP_NODELAY by default, and allow clients to override it? That's fine by me, I'll accept a pull request

socketpair commented 9 years ago

No, option is not needed. Since you never send big chunk of data with multiple send syscalls, TCP_NODELAY will not hurt any way. So I consider you should always set this flag. This flag really is really hurt in modern applications since these app use internal buffering before sending and never repeatedly call send syscall with small portions of data.

benjamin-hodgson commented 9 years ago

I'm happy to set the flag by default, but we really should provide a means by which to override it. It doesn't do any harm to make it overridable, and in my experience people will always want to reconfigure this sort of thing. No one likes working with overly-opinionated software.