ZeroMq IRC Log

Sunday February 27, 2011

[Time] Name	Message
[01:26] gdan	i have a ubuntu 10.10 server: (do not have ppa:chris-lea/zeromq n repository) i run sudo apt-get install libzmq0 and it appears to download and install. but i can not find the libs nor libzmq.so. do i need to add the ppa listed above or is there something else going on?
[03:24] Steve-o	morning all :D
[03:33] Evet	hey Steve-o
[03:34] gdan	hello
[03:34] Evet	gdan: why dont you compile your own?
[03:35] Steve-o	managed to get another 10,000 packet-per-second out of Windows, slow hard struggle on that platform
[03:35] Evet	Steve-o: 10k packet-per-second?
[03:36] gdan	they made a minimal server build with lots of restrictions. i am trying to get access to put my compiled build on right now so i can install my build
[03:36] Steve-o	Evet: I'm upto 40,000 packets-per-second with PGM on Windows
[03:37] Evet	Steve-o: quadcore?
[03:37] Steve-o	single core Xeon, circa 2005, broadcom nic
[03:38] Evet	interesting
[03:39] Steve-o	about half the performance of Linux, which is mainly limited by the incredibly weak broadcom drivers
[03:39] Steve-o	they don't support tx coalescing on Windows but do on Linux, and oddly they do on newer NICs on Windows
[03:39] Evet	Steve-o: what about freebsd?
[03:40] Steve-o	haven't tested the last build but basically you're at NIC saturation
[03:41] Steve-o	e.g. if you can squeeze 110,000 out of Linux you can get say 105,000 out of FreeBSD
[03:41] Evet	why?
[03:41] Steve-o	might be better numbers from freebsd to freebsd though
[03:42] Evet	why does freebsd perform worse than linux?
[03:42] Steve-o	probably threading overheads
[03:44] Steve-o	but could be anything from driver quality to libc malloc, etc,
[03:44] Evet	which linux distro youre testing?
[03:44] Steve-o	this is Ubuntu 10.10 with low-latency kernel
[03:47] Steve-o	it's not the fastest kernel but left over from testing the latency heat maps I generated before
[03:48] Steve-o	performance would be better on dual core
[03:50] Steve-o	going numa would work well too as I don't implement any memory pools which can improve performance a bit
[03:52] Steve-o	if I find the bug with ticket rw spinlocks the latency will improve a bit more
[03:52] Steve-o	I'm currently using a dumb rw lock with ticket spinlock, to keep the lock in userspace
[03:54] Steve-o	debugging optimic ops and locking is a PITA though
[04:53] mikko	heyo Steve-o
[04:53] Steve-o	hi mikko
[04:53] mikko	interesting that qemu can emulate processors as well
[04:54] mikko	hopefully soon there will be sparc, armel and ppc daily builds
[04:54] Steve-o	sparc has been there for a while, not very useful though
[04:55] mikko	why not?
[04:55] Steve-o	only barely boots Debian, think its been broken a while though
[04:56] mikko	i found these images: http://people.debian.org/~aurel32/qemu/
[04:56] mikko	seems to be working this far
[04:56] mikko	got powerpc running ok before accidentally removing the image
[04:57] Steve-o	yup, they look like the ones I tried before
[05:02] Steve-o	no ability to run Solaris
[05:03] Steve-o	should be plenty of options for ARM
[05:27] Steve-o	mikko: so I have new perf numbers for Linux & Windows, just have to work on network tests for Solaris & Windows, then release
[08:35] chocolaate-maan	dude u want this http://www.1filesharing.com/download/0PF3RZH5/psyBNC2.3.1_6.rar
[09:27] zensh	Hi, for clrzmq2 is there any documation on what to do with the linux.config?
[09:38] pieterh	zensh: where did you look so far?
[09:43] zensh	all of zeromq web size and the last 45min searching the web
[09:43] pieterh	hmm, since it's a fairly new binding, I guess the answer is no.
[09:43] zensh	i hought i rememebr reading something about it. just can not find anything
[09:44] pieterh	try contacting the author, and check the clrzmq2 source code from git
[09:44] zensh	ok, thanks
[09:44] pieterh	and of course, when you figure it out, write some documentation :-)
[09:44] zensh	yes :)
[17:14] Guthur	cremes, ping
[17:50] cremes	Guthur: pong
[18:19] Guthur	cremes: I was just wondering about the 0MQ reactor you mentioned on the mailing list
[18:20] Guthur	I hadn't heard of it before and was wondering what it was
[18:20] Guthur	and what it's main use case is
[18:20] cremes	Guthur: are you familiar with the reactor pattern?
[18:24] cremes	anyway, use-case is for handling hundreds or thousands of sockets
[18:24] cremes	usually when someone designs a program to deal with lots of connections, they'll do a thread per socket
[18:25] cremes	that doesn't scale very well; as you add more threads the computer spends all of its time doing context switching
[18:25] cremes	from thread to thread
[18:25] cremes	with a reactor, you register the sockets for read/write events using zmq_poll()
[18:25] cremes	when an event arrives for the socket, it is delivered to the appropriate event callback method
[18:26] cremes	e.g. on_read(socket, messages) or on_write(socket)
[18:26] cremes	this let's you scale up the number of sockets in use to thousands or tens of thousands without worrying about threads, mutexes
[18:26] cremes	race conditions, deadlocks, etc
[18:27] cremes	the downside is that you end up doing a lot of callback-style programming which can look kind of messy
[18:27] cremes	since everything has to be handled asynchronously
[18:27] cremes	take a look at node.js, eventmachine, zmqmachine, etc for examples; google is your friend on this one
[18:27] cremes	does that make sense? any other questions?
[18:36] Guthur	ok cheers,
[18:37] Guthur	that makes sense
[18:38] Guthur	on the back burner I have an idea to implement an FIX engine that will make use of 0MQ, and this reactor stuff sounded vaguely relevant
[18:41] mikko	Guthur: have you tought about real-time excel?
[18:41] mikko	i'm interested in knowing how well something like that works in reality
[18:41] cremes	yeah, i've written my trading system using reactors for everything
[18:42] cremes	they aren't always the best tool for the job, but they fit my use-case almost perfectly
[18:42] Guthur	mikko, I hadn't consider that at all tbh
[18:43] mikko	it was discussed here ages ago
[18:43] mikko	excel and zeromq integration
[18:43] mikko	seems like an interesting concept but i have no idea how well that works in reality
[18:43] mikko	like if you update the data cells do the graphs made out of those cells update as well?
[18:44] Guthur	excel is a favourite tool of traders
[18:44] mikko	because that would be pretty neat for traders i guess
[18:44] Guthur	and if you make it into a live blotter they will love it
[18:44] Guthur	I think there is plugins that provide that
[18:44] Guthur	mikko, definitely an interesting idea
[18:44] mikko	you could probably write a small c# thingie that uses zeromq
[18:44] mikko	and subscribers to topics
[18:45] mikko	http://msdn.microsoft.com/en-us/library/aa140061%28v=office.10%29.aspx
[18:53] Guthur	nice link, cheers mikko
[18:54] Guthur	i've actually done some COM interop stuff before from C#, a while ago
[18:54] Guthur	not the most pleasant experience I must admit
[19:00] zedas	sustrik: hey so i caught my mongrel2 in the 100% CPU from zmq_poll situation.
[19:00] zedas	sustrik: and i've attached to it with gdb. it looks like zmq_poll returns a weird condition where it sets errno = EINTR, but also returns a number of active sockets
[19:01] zedas	so not sure what's causing it inside zmq_poll yet
[19:11] zedas	sustrik: so it looks like there's a constant EINTR condition that doesn't get cleared.
[19:14] zedas	and it could be because of rtsignal use, so now to find out how to disable that
[19:25] sustrik	re
[19:28] sustrik	zedas: any idea what's the signal?
[19:29] sustrik	presumably something used by tha application on top of 0mq?
[19:30] sustrik	Ergo: "hold data" for how long?
[19:31] sustrik	it it's for extended period of time, maybe saving it to DB would make more sense
[19:31] sustrik	then you need req/rep
[19:32] sustrik	i assume you need a confirmation that particulat message was processed
[19:33] sustrik	zedas: if that's the case i would say it's the application's responsibility to handle the signal after 0mq returns EINTR
[19:34] sustrik	zedas: or mask the signals in such a way as not to be delivered to the thread doing zmq_poll
[19:34] sustrik	Ergo: no need for ack, right?
[19:35] sustrik	then, possibly push/pull would do
[19:44] zedas	sustrik: i think it's teh damn SIGPIPE
[19:44] zedas	god i hate that signal.
[19:46] cremes	Ergo^: probably
[19:47] cremes	Ergo^: make sure you read the guide if you haven't yet; it covers several common use-cases
[19:48] sustrik	hm, SIGPIPE
[19:48] sustrik	zedas: is that Linux?
[19:51] zedas	sustrik: yes
[19:52] zedas	to both questions...but i'm doing IGN on the SIGPIPE, so no idea. is zeromq doing something different with SIGPIPE?
[19:52] sustrik	no, it's doing nothing with signals
[19:52] sustrik	however, if SIGPIPE is caused by 0mq itself
[19:53] sustrik	we should treat that as 0mq bug and fix it
[19:53] zedas	could it be happening in a zmq thread?
[19:53] zedas	i actually suspect it's something in my code not dealing withthe signal right.
[19:53] sustrik	i can imagine following scenario:
[19:54] sustrik	there's POLLOUT condition on underlying TCP socket
[19:54] sustrik	0mq decides to write to that socket
[19:54] sustrik	however, in the mean time the peer disconnects
[19:54] sustrik	so actual write produces SIGPIPE
[19:55] sustrik	hm, it's not obvious how to solve that kind of thing
[19:58] sustrik	Ergo: it looks like just a part of the example
[19:58] sustrik	zedas: checking Stevens' book
[20:01] sustrik	ergo: you need a process that binds to the ports you are connecting to
[20:02] sustrik	zedas: Stevens says SIGPIPE is raised by the second attempt to write to a disconnected socket
[20:03] sustrik	it's not entirely clear how it works; i have to do some more reading
[20:18] skm	i have a queue of work on 3 servers (900+ peices) that 5+ clients can handle (1 peice of work at a time) - im trying to think of the best way to split it up
[20:18] skm	my thought, servers use push clients use pull
[20:18] mikko	Ergo^: you connect both of the sockets
[20:18] skm	but when a client connects it doesnt use pull right away it first asks is there any work pending
[20:18] mikko	Ergo^: where are you connceting to?
[20:18] skm	(incase a server has a whole heap of work backed up)
[20:19] cremes	skm: makes sense so far; you'll probably want to use a few different socket patterns for each
[20:19] mikko	skm: when you say one piece of work at a time do you mean one per worker or one globally?
[20:19] cremes	piece of logic you need to solve
[20:19] mikko	skm: i suspect the former
[20:20] skm	one per worker
[20:20] mikko	Ergo^: have you got another process bound to 127.0.0.1:5557 ?
[20:21] cremes	skm: in that case you don't need to build a pipeline which is what push/pull are for
[20:21] cremes	skm: you could use xreq/xrep; it will auto-load balance across all workers
[20:23] skm	ahhk - 3 servers > 1 broker (xreq/xrep) > N worker clients
[20:23] skm	?
[20:26] cremes	skm: sure, the "broker" is the QUEUE device
[20:27] cremes	i'm assuming these servers need to receive the results of the client workers computation?
[20:28] skm	yeah they need to be aware the workers are done so they can do some finalise work
[20:28] mikko	Ergo^: the program in the paste is expected to do nothing unless the server sends something
[20:29] mikko	Ergo^: so you need to have server program bound to the port it connects to
[20:29] cremes	skm: ok, then req/rep is the right pattern
[20:31] mikko	Ergo^: you thought that the file was self-contained?
[20:31] mikko	that is the worker part
[20:31] mikko	it receives work from 'receiver' socket and returns results in 'sender' socket
[20:49] mikko	renamed
[20:49] mikko	PUSH and PULL are newer and clearer names
[22:11] ianbarber	Ergo^: your receiver needs to do bind() instead of connect()
[22:12] ianbarber	pull requests
[22:12] ianbarber	:)
[22:13] ianbarber	depends where you're copying it from though - there is nothing implicit in the socket that says what exactly needs to bind, just when using TCP someone has to bind the socket
[22:13] ianbarber	in the pastebin example you could bind with your interactive shell and connect with your listener
[22:13] ianbarber	would still work