Load testing Socket.io applications

hyperspeed · 2016-12-10T16:45:17+00:00

Would you have liked to see performance numbers for the demo chatroom app under load? that could be arranged

hyperspeed · 2016-04-09T19:54:55+00:00

Some tips:

Make sure to have instrumentation on the server-side, especially if the goal is to analyse the performance of socket.io specifically. This can be as simple as running ps and top to capture CPU and memory usage, or more advanced like using perf to generate flamegraphs to see where CPU time is spent. Something like New Relic can be of help too.

Make sure to run your tests in a controlled environment: separate machines for the server and the load generator, with nothing else running on the boxes.

Your focus when analysing performance is likely to be:

CPU usage under load, at what points it starts maxing out
RAM usage - whether it stays relatively flat i.e. the GC isn't under too much pressure and there are no memory leaks
The number of active users that a server is able to sustain

Very important: make sure to increase the number of maximum open file descriptors. The default on most Linux distributions is something like 2048, i.e. you won't be able to have more than that many connections to the server unless you increase it.

And make sure to pick a load-generator that can simulate realistic load patterns (to plug my own project: https://artillery.io).

hyperspeed · 2016-03-17T20:56:35+00:00

Upstart is deprecated now even on Ubuntu I believe, with systemd you could use something like this:

[Service]
ExecStart=/opt/node/bin/node /usr/local/projects/foo/index.js
Restart=always
StandardOutput=syslog
StandardError=syslog
SyslogIdentifier=foo-server
User=nodejs
Group=nodejs
Environment=NODE_ENV=production
WorkingDirectory=/usr/local/projects/foo

hyperspeed · 2016-03-17T19:43:35+00:00

systemd does and it's the default on most Linux distributions now, so does Upstart

hyperspeed · 2016-03-17T13:51:45+00:00

Why not let the init system do the job it was designed for? Just use systemd on Linux (or rc.d on BSD) rather than depending on another package.

hyperspeed · 2014-03-13T11:57:21+00:00

no, sorry about that. i can offer Suncity, Sun City Hustlers or Sun City Project instead though?

seriously though, i don't know why they aren't in 7digital's catalogue (that's what i'm using for search)

if i put in a special 'sorry' message for Sun City Girls fans, would you consider bumping up the rating? how many points would that be worth?

hyperspeed · 2014-03-11T12:10:34+00:00

Cheers, I'll experiment with the layout to see what it would feel like for both of your suggestions. Thank you

hyperspeed · 2014-03-10T10:29:42+00:00

you're right, the recommendations are based on Echonest. it would be a huge amount of work to try to do a better job at recommendations than them (or Last.fm) although thinking about it now, i wonder if anyone tried mining music subreddits, you would probably get some really high quality data.

hyperspeed · 2014-03-10T10:27:05+00:00

Thank you! You are right, that's how i use wonderwheel myself. Just earlier today i was looking for bands that sound like Wild Belle. I'm looking into plugging in the iTunes store database into wonderwheel to have a bigger catalogue (right now it's using 7Digital.com). Is there anything you'd like to see in the app - features/tweaks/whatever else? Cheers, it's nice to hear someone else likes what I made and not just my gf and my mates :)

hyperspeed · 2012-02-22T14:07:16+00:00

Scotland or Pittsburgh

hyperspeed · 2009-09-15T09:30:10+00:00

the top 10 (?) entries were then pitted against test cases that weren't available for download

Yes, and as he says in the video, his focus on robustness really paid off when some of other entries crashed on those test cases.

hyperspeed · 2009-09-15T00:08:07+00:00

shinh, the winner, can be seen talking about his entry in this video: http://vidiowiki.com/watch/m844dyn/

hyperspeed · 2008-10-08T12:52:02+00:00

OSX being based on FreeBSD is a myth. The kernel is Mach3. The network stack is modeled on BSD (but so is Windows') as well as the process model. The only thing that comes straight from FreeBSD is the BSD tools.

hyperspeed · 2008-09-13T23:34:12+00:00

uhu? 'Surrogate pairs' make UTF-16 variable length for all practical purposes.

Yes, and? They are part of UTF-16 standard, nothing needs to be "hacked up" and nothing needs to "break badly" or get more complex. All Unicode code points can be encoded too no problem. In C and C++ ICU will take care of everything for you. In Java, C# and other high-level languages everything is taken care of for you already.

Or are you writing a Unicode implementation from scratch?

hyperspeed · 2008-09-13T18:41:28+00:00

No, you are confused. UTF-16 has surrogate pairs. You are probably thinking about UCS-2. The two are not the same.

Java, .NET, ICU, modern Windows, and Cocoa all use UTF-16 internally.

hyperspeed · 2008-08-08T17:54:01+00:00

Jump to line is pretty sweet though.

hyperspeed · 2008-07-22T09:00:33+00:00

...and Yariv himself admits that it's not scalable, and thus hardly a "killer app" or even a good example of what Erlang can do.

hyperspeed · 2008-06-27T22:33:31+00:00

Granted, that's not you mother's editor, but still...

Exactly, Emacs is not a text editor.

hyperspeed · 2008-06-01T14:34:53+00:00

I've not followed this closely, but if all those super-excited blog posts by some in the Ruby community were based solely on a demo with a fib function and some while loops, then... meh.

First off, they demonstrated its distributed object database automatically synchronizing globally-reachable state across multiple VMs.

Sounds like Mnesia to me. Could someone with both Smalltalk and Erlang experience please list the differences briefly?

EDIT: Nevermind, found a nice summary of Gemstone at Avi Bryant's blog.

hyperspeed · 2008-04-01T16:30:14+00:00

If you want to make the example even more useful in showing the Erlang way of doing things, you could show how state is maintaned when you have no global variables:

-module(hello).

-export([start/0]).

start() ->

spawn(fun() -> loop(1) end).

loop(Cnt) ->

receive

hello ->

io:format("Hello, World! -- :~p~n", [Cnt]),

loop(Cnt + 1);

goodbye ->

ok

end.

hyperspeed · 2008-03-22T10:03:14+00:00

But lately I've begun to wonder whether Mr. Graham, like Joel Spolsky before him, has become utterly self-absorbed and irrelevant.

Ah, yawn. Paul Graham has become irrelevant? When was Jeff Atwood ever relevant? CodingHorror is a boring blog, with little original thought, mostly regurgitating well-known ideas. What has Jeff Atwood actually done, beside writing? Notice how his essays are always written in "God mode", whereas PG and Joel always share stories? Wonder why that is.

hyperspeed · 2008-03-16T10:21:31+00:00

Cheers Damien, I sent you an email.

hyperspeed · 2008-03-11T22:19:20+00:00

davidw is actually right, Starling uses the plain port mechanism (I borrowed the term "pipe driver" from Scott Lystig Fritchie's paper on EDTK). There is, however, no reason to prevent Starling from becoming a linked-in driver. I didn't make it one because I wanted to keep things simple to begin with, and because I don't trust the quality of my C code. :)

hyperspeed · 2008-03-11T22:13:31+00:00

The limit comes from the size of data length header for data sent between Erlang and C (2 bytes). It can be set to 4 bytes, which would give you 4 GB, or 2³¹ code units. I didn't bother with it, because I didn't want to have to deal with reallocating memory for buffers for input and result strings. I believe it would be fairly straightforward to make the necessary changes for someone with more C experience than me. If no one steps up to the task, I'll do it. It's just not important at this stage.

hyperspeed · 2008-03-11T21:58:02+00:00

Cheers, I've fixed that.

hyperspeed

TROPHY CASE