Node.js powers comet for plurk (100k+ users at once)

http://amix.dk/blog/post/19490#Plurk-Instant-conversations-using-comet

by olegp • 16 years ago

87 26 16 years ago

amix7• 16 years ago

I am here to answer questions. I will start by sharing some implementation details:

- we use long polling, but will add WebSocket support once we get more browsers that support it. The code to make it work is shared here: http://amix.dk/blog/post/19489

- we had a smaller comet system in the past that was based on Java + JBoss Netty. It didn't scale that well (used ~10x time the memory node.js solution and had a lot of quirks, like lost connections). Generally thought Netty worked "ok", but I would recommend anyone doing anything serious to look at node.js

- node.js feels VERY natural, but it could be because I had coded so much in JavaScript :)

- I have done a presentation on comet with node.js+V8 to the Taipei Open Source Group which you can check out here: http://amix.dk/blog/post/19484

The technology is there to build next generation web-applications, what are you waiting for? :)

atarashi• 16 years ago

In your Comet with node.js and V8 presentation, you said that Plurk was originally using Netty to handle 200k open connections. About how much memory was that consuming?

amix7• 16 years ago

10-20GB depending on the traffic level. node.js uses around 10x less than that - even if it's a much more sophisticated solution.

axod3• 16 years ago

What hardware are you using behind it? eg how much resources are needed to support N users?

amix7• 16 years ago

1 server (32GB of RAM, quad core). I don't know how much 1 server can scale to, but it's a lot, since a lot of the connections are idle a lot of the time.

tr4nslator• 16 years ago

Do you anticipate that the use of WebSockets will improve performance? If so, can you estimate to what degree?

amix7• 16 years ago

It will since you don't need to open and close connections all the time. I can't estimate at what degree, but I think the communication will be much faster since currently some time is used to re-create connections.

axod3• 16 years ago

Not to pedal my own wares, but... ;)

http://axod.blogspot.com/2009/12/websocket-some-numbers.html

Also a caveat followup - websocket don't play nice with some proxies/nat/firewall setups. Either need https, or fallback on comet.

liuliu2• 16 years ago

how do you access data storage backend (redis, memcached, your lightcloud and mysql) wth node.js? any suggestions?

Edit: plus, I am confused about the presentation on comparison with Tornado slide. It seems Tornado has higher transfer rate. And after all, they just do a thin layer on top of epoll, what's the penalty here?

amix7• 16 years ago

Given how young node.js is it has a lot of modules including:

Redis http://github.com/fictorial/redis-node-client

memcache: http://github.com/elbart/node-memcache

MySQL support using DBSlayer

And it's fairly easy to implement other stuff using node.js's TCP module. This said, it could definitely use more modules, but it's a young project and I am sure they will come.

mcantelon2• 16 years ago

Also MongoDB support: http://wiki.github.com/orlandov/node-mongodb/ (bleeding edge, but is working well for my experimental project)

tumult2• 16 years ago

What drove you to writing backend code in JavaScript? Having written several projects (client-side, but minimal DOM junk) in JS, I cringe at the thought of having to use it where it's not required. Some people really seem to like their JS, though, so I'm wondering what drew you to it?

amix7• 16 years ago

There are two reasons why I picked JavaScript. First, V8+node.js is an amazing runtime system. One should remember that V8 is implemented by a highly skilled Google team that's led by Lars Bak - who was the lead architect for Java's HotSpot VM (the current VM that's used in Java...) So first choice, performance. node.js is also very small in size, so I figured out I could patch if anything wasn't working.

The second reason to pick JavaScript is that it's already geared towards event based programming, because of following things:

   events in browsers and
   closures are a natural part of the language, e.g.
   document.addEventListener("click", function()...

Event based programming is needed to implement highly scaleable non-blocking servers. So JavaScript is a really good match...

And really, JavaScript is a great language and it can emulate almost any paradigm that you may like. node.js also introduces a module system which makes it much easier to manage code. JavaScript isn't perfect and there's tons of bad code written for it, but it's possible to create beautiful code in JavaScript :-)

aschobel• 16 years ago

Have you used Thrift w/ node.js?

There seems to be some JavaScript support for Thrift, this would be a great way to have node.js fit in with ones architecture.

https://issues.apache.org/jira/browse/THRIFT-550

Also what are you using for your base libraries?

For example one needs RFC3339 date support, can you just plug in something like Google Closure Library?

http://code.google.com/closure/library/

deepu_k• 16 years ago

i am working on using closure libraries on backend. converted some and seems to be working fine.

stephen• 16 years ago

Do you have any insights/opinions on why node.js beats Netty? It is something inherent in the JVM or is Netty's implementation flawed/not ideal for your scenario?

(E.g. I'm a node.js newbie, but my understanding is that it doesn't have the io thread/worker thread pool, pipeline/handler framework that Netty does. Still reading about it.)

liuliu2• 16 years ago

node.js is surely cutting-edge. But I am more interested to see any implementations of Google's Go for COMET in large website practice.

brainfucker• 16 years ago

Are you using hashlib library (http://github.com/brainfucker/hashlib) (I just wondering=)

Did you need some other functionality, and also have you any interest of new modules for node?

Node.js powers comet for plurk (100k+ users at once)

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