ZeroMq IRC Log

Thursday December 23, 2010

[Time] Name	Message
[01:26] dos000	how does the network/tcp driver deliver packets for the same flow when a new packet arrives ? does it look up a hash tree to find the correct app listening on that socket ?
[01:26] dos000	i have to do kinda same thing ... and zmq does also
[01:47] Steve-o	morning all
[02:15] Skaag	morning Steve-o
[04:45] NoobFukaire	I'm trying to test out the hello world stuff for C++ and zeromq
[04:45] NoobFukaire	the server binds and I can see it's there with netstat (and I can telnet into it)
[04:45] NoobFukaire	but when I connect with the client, I get Assertion failed: fetched (rep.cpp:232)
[04:46] NoobFukaire	which is:
[04:46] NoobFukaire	// Get next part of the message.
[04:46] NoobFukaire	bool fetched = in_pipes [current]->read (msg_);
[04:46] NoobFukaire	zmq_assert (fetched);
[04:46] NoobFukaire	I'm not sure whats up with this lib?
[04:49] NoobFukaire	http://pastebin.com/piwK7gxL
[04:49] NoobFukaire	the stack trace
[04:54] NoobFukaire	https://github.com/imatix/zguide/blob/master/examples/C++/hwserver.cpp
[04:54] NoobFukaire	https://github.com/imatix/zguide/blob/master/examples/C++/hwclient.cpp
[04:54] NoobFukaire	that's the code
[05:07] NoobFukaire	okay nm, it had to do with some of my build paths
[06:55] andrewvc	cremes: you around?
[07:59] sustrik	hi mikko!
[08:16] mikko	sustrik: hi
[08:16] sustrik	morning
[08:16] sustrik	there's a build patch from steve in the ML
[08:16] sustrik	can i apply it?
[08:16] mikko	steve-o?
[08:16] sustrik	yes
[08:17] mikko	i'll review today if thats ok
[08:17] sustrik	sure, no haste
[08:17] mikko	i would like to change the way we build openpgm
[08:17] sustrik	what's the idea?
[08:17] mikko	it seems that we are duplicating a lot of work at the moment
[08:17] mikko	somehow that doesn't feel right
[08:17] sustrik	yes, we are
[08:18] sustrik	the alternative was to use scons
[08:18] sustrik	which create additional dependencies
[08:18] sustrik	any better idea?
[08:19] mikko	i was thinking about two options:
[08:19] mikko	a) invoke scons
[08:19] mikko	b) isolate openpgm flags to their own files
[08:19] sustrik	a) IMO is just shifting work from 0mq maintainers to 0mq users
[08:19] mikko	i think that having large amount of conditionals in the Makefile.am isn't maintainable in the long run. also makes patching harder
[08:20] sustrik	yes, agreed
[08:20] sustrik	would b) help with that?
[08:20] mikko	yes
[08:20] mikko	we would have something like foreign/Makefile.linux.am
[08:21] mikko	and include from configure.in based on OS/compiler
[08:21] sustrik	i see
[08:21] mikko	not sure if that works yet but ill try today
[08:21] sustrik	ok
[08:21] mikko	that way we could track openpgm build changes more easily
[08:21] sustrik	ack
[08:23] mikko	also, we should add support for solaris / freebsd with openpgm and the other steve is working on os x build
[08:23] mikko	so that's 5 conditionals in Makefile
[08:24] sustrik	sounds messy
[08:25] mikko	yeah, that was originally why i wanted to investigate invoking scons
[08:25] mikko	as steve has done a lot of work with different platforms / compilers to get the build working
[16:55] NoobFukaire	whats the best way to implement bidirectional messaging with zeromq?
[16:56] NoobFukaire	two REQ-REP sockets?
[16:56] NoobFukaire	I need either client to be able to send and receive messages at any point
[17:10] sustrik	what are you trying to do?
[17:11] NoobFukaire	I have two processes that need to exchange event information
[17:11] NoobFukaire	those events can be created at any time, on either end
[17:12] NoobFukaire	I wish there was some non blocking way to process inbound messages
[17:12] NoobFukaire	with zeromq
[17:16] sustrik	is that some kind of "multicast bus" scenario?
[17:16] sustrik	i.e. any message published by anyone is received by anyone else?
[17:17] NoobFukaire	no, it's basically client server
[17:17] NoobFukaire	right now it's 1:1 but there might be multiple clients in the future
[17:17] NoobFukaire	I'm find with 1:1 for now though
[17:17] sustrik	so it's 1 server and N clients
[17:17] NoobFukaire	*fine
[17:18] NoobFukaire	I'll refactor for multiple clients when the time comes and I know zeromq better ;)
[17:18] sustrik	what kind of interactions there are between server & client?
[17:18] sustrik	server publishing stream of events to be received by each client?
[17:18] NoobFukaire	I'm sending google protobuf messages back and forth
[17:19] sustrik	back & forth = client initiated handshake?
[17:19] NoobFukaire	they're just "events" they can be generated asynchronously by either side
[17:19] sustrik	0mq doesn't work that way, you have to identify patterns in the communications
[17:19] sustrik	handshakes
[17:20] sustrik	data distribution
[17:20] sustrik	load balancing
[17:20] sustrik	and similar
[17:20] NoobFukaire	okay I don't care about any of that
[17:20] NoobFukaire	this is about two process that exist on the same machine
[17:20] NoobFukaire	and need to communicate
[17:20] sustrik	use TCP then
[17:20] NoobFukaire	there will never be a performance issue
[17:20] NoobFukaire	gagh
[17:21] sustrik	well, 0mq needs to know what you are trying to achieve to help you
[17:21] spht	NoobFukaire: Just because you're scenario is 1:1 doesn't mean a 1:N solution doesn't fit
[17:21] spht	s/you're/your
[17:21] sustrik	just saying "anything" doesn't work
[17:21] NoobFukaire	that's true but I'm just trying to keep things as simple as possible until I'm more familiar with zeromq
[17:22] sustrik	you can use PAIR socket
[17:22] sustrik	it's strictly 1:1
[17:22] sustrik	but there are some features missing, like auto-reconnection etc.
[17:23] NoobFukaire	spht: is there no way to check read zeromq input in a non blocking fashion?
[17:24] NoobFukaire	I have a function that gets called at a regular interval
[17:24] NoobFukaire	ideally, I'd like to have that check for input, process it and then process outbound messages
[17:24] sustrik	use ZMQ_NOBLOCK flag in recv()
[17:24] spht	NoobFukaire: you can setup zeromq non-blocking IIRC,
[17:24] spht	what sustrik said ;)
[17:24] NoobFukaire	right now it's blocking, so once recv is called, it blocks until input is returned
[17:25] NoobFukaire	what did he say
[17:25] spht	ZMQ_NOBLOCK
[17:25] NoobFukaire	thanks
[17:26] spht	but if your app is event driven to start with maybe you want to hook up the zeromq fd's into your runloop/reactor or what you use
[17:26] spht	sustrik: IIRC thats possible, right?
[17:27] spht	I'm a newbie myself so I hope I'm not spreading lies ;)
[17:29] NoobFukaire	in my case, latency is very important and networking is not required at all
[17:29] NoobFukaire	because these events may have UI functionality executed as a result
[17:33] sustrik	spht: yes, it's possible
[17:34] sustrik	VoobFukaire: for best latency you can collacate the sender and receiver in the same process
[17:34] sustrik	each running is a different thread
[17:35] spht	And for low latency you probably do not want to poll for new messages (as I guess was what you wanted with the non-blocking sockets)
[17:52] NoobFukaire	I need to keep the UI responses ideally under ~100ms to eliminate any lag for the end user
[17:52] NoobFukaire	granted the UI stuff itself is done in the toolkit's thread, so these events are more of a "trigger" for those
[17:53] NoobFukaire	thank you for your help and suggestions
[17:54] NoobFukaire	ZMQ_NOBLOCK seems to do what I want with nonblocking io, thank you sustrik
[17:57] sustrik	you are welcome
[18:58] mikko	sustrik: why doesn't pair auto-reconnect?
[18:59] sustrik	nobody implemented it :)
[18:59] mikko	is that a hint ?
[18:59] mikko	:)
[18:59] sustrik	:)
[18:59] mikko	drove 800km today
[18:59] sustrik	well, the thing is that PAIR is a socket type
[18:59] sustrik	that is most prone to misuse
[19:00] sustrik	so i quite like it being slightly broken
[19:00] mikko	i abuse pair heavily in my program
[19:00] sustrik	:)
[19:00] sustrik	where have you gone?
[19:00] mikko	dark place
[19:00] sustrik	finland?
[19:00] mikko	yeah
[19:01] sustrik	800km, than must be somewhere behing polar cirscle
[19:01] sustrik	circle
[19:01] mikko	drove to helsinki and back
[19:01] mikko	just to find out that my friend's flight is so late that we drove back
[19:01] sustrik	:\|
[19:01] mikko	now he might even miss the last bus
[19:02] sustrik	what's exactly the problem with flights?
[19:02] sustrik	too cold or what?
[19:03] mikko	he is flying from london heathrow
[19:03] mikko	the problem at heathrow is incompetence
[19:03] sustrik	i guess so
[19:04] mikko	it's not -29.5 celsius where i am
[19:04] mikko	and all airports open
[19:04] sustrik	actually, it's nice warm here in Bratislava today
[19:05] sustrik	temperature went up by 20 degress or so
[19:05] sustrik	btw, i'm messing with linux kernel
[19:06] sustrik	the experience so far is that in comparison 0MQ codebase is pretty sane and well documented
[19:07] mikko	heheh
[19:07] mikko	im not suprised
[19:08] sustrik	well, it's an old project so some amount of messiness is expected
[19:08] sustrik	but the network stack seems to have no comments at all
[19:08] sustrik	:(
[19:19] mikko	dark arts
[22:06] andrewvc	cremes: you around?