The Node.js Scalability Myth

Presentation given on 26.04.2012 at MixIT conference in Lyon, France.

Transcript

1. The Node.js
   Scalability Myth
   Felix Geisendörfer
   26.04.2012 at MixIT Conference (Lyon, France)
   

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2. (@)felixge(.de)
   

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3. core contributor
   

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4. transloadit.com
   (using node since v0.0.6)
   

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5. History
   

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6. Ryan Dahl starts the node project (first commit)
   Feb 16, 2009
   

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7. Discovered node.js (v0.0.6)
   ~June, 2009
   

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9. Core Contributor
   &
   Module Author
   node-mysql node-formidable
   + 30 other modules
   

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10. Isaac Schlueter starts the npm package manager
    (first commit)
    Sep 29, 2009
    

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11. Ryan’s talk at JSConf.EU gets people excited about node
    Nov 7, 2009
    

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12. (c) @substack
    Jan 30, 2012
    Ryan appoints Isaac to lead node.js
    

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13. Topic of this Talk
    

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14. I need to build an
    über-scalable web
    service. It will be the
    next big thing!
    

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15. Easy! I will use
    node.js and
    MongoDB!
    

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16. Easy! I will use
    node.js and
    MongoDB!
    

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17. Because node.js is
    “scalable”, right?
    

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19. Audience?
    

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20. Node.js?
    

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21. Are you measuring app performance in production?
    

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22. 1000
    req / s
    

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23. 100
    req / s
    

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24. 10
    req / s
    

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25. 10 requests / per second =
    864000 requests / day
    10
    req / s
    

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26. The End?
    

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27. I REALLY need to build
    an über-scalable web
    service!!11!1
    

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28. Scalability
    

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29. (c) @substack
    

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30. The Node.js Scalability Myth
    • Threads don’t scale
    • Event loops do
    

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31. The Node.js Scalability Myth
    • Threads don’t scale
    • Event loops do
    (Probably) not true in 2012
    (Very likely) not relevant
    

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32. More relevant
    • Understanding your tools
    • Using the right tool for the job
    

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33. Node’s Concurrency
    Model
    

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34. Node’s Concurrency Model
    1 var http = require('http');
    2
    3 http.createServer(function(req, res) {
    4 res.end('Hello World');
    5 }).listen(8080);
    server.js
    

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35. Node’s Concurrency Model
    $ node server.js
    

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36. Node’s Concurrency Model
    • Node loads server.js from disk -> v8 compiles & executes
    • listen() allocates and binds a file descriptor
    • Event Loops starts running
    

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37. Node’s Concurrency Model
    1 while (true) {
    2 int r = select(nfds, readfds, writefds, errorfds, 0);
    3 if (r === 0) {
    4 continue;
    5 }
    6
    7 // Figure out which fds had activity, accept() on server fds, read() on
    // connection fds, write() queued writes
    8 }
    Abstracted by libuv
    Different on Windows
    

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38. Node’s Concurrency Model
    • Cooperative multitasking
    • Low memory usage
    • Fast / efficient
    • Simple (compared to threads)
    

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39. Vertical Scalability
    

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40. Adding more resources to a single node
    

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41. Vertical Scalability
    • CPU
    • GPUs
    • Memory
    • Disk
    • Network
    

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42. CPU
    

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43. CPU (v8)
    • V8 compiles JS to Assembly
    • Just-in-time compilation (JIT)
    • Does pretty well in those language benchmarks
    

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44. Computers of the
    future will have
    hundreds of cores!
    

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45. CPU
    • Node is single threaded (runs on a single CPU)
    • No shared memory
    

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46. But ...
    

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47. Does your problem
    require shared
    memory?
    

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48. If yes: Don’t use node
    

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49. And: Good Luck
    

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50. If no:
    child_process.fork()
    

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51. Redis / ZeroMQ are your
    friends
    

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52. GPUs
    

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53. GPUs
    • No support in node itself
    • node-cuda addon by Kashif Rasul
    

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54. Memory
    

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55. Memory
    • No hard memory limit on 64 bit (since node-0.6 / v8-3.7)
    • JS is a garbage collected language (avoid huge heaps)
    • Buffers do not count towards heap
    

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56. Network
    

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57. Network
    • Node’s concurrency model is optimized for networking
    • Good at fully saturating available network resources
    

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58. Disk
    

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59. Disk
    • Done in thread pool
    • Unfortunately along with DNS at this point
    • Throughput ok, but not ideal yet
    • sendfile() not working yet
    

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60. Does node scale vertically?
    

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61. Yeah, good enough
    

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62. Horizontal Scalability
    

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63. Adding more nodes to a system
    

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64. Bad News
    

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65. Node.js has no horizontal scaling features
    

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66. Even worse
    

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67. This s#@t is really hard
    

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68. Problems
    • De-coupling / encapsulation
    • CAP Theorem
    • System Automation
    

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69. ...
    

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70. Good Luck
    

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71. One tip
    

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72. Monitor & Measure!
    • Collect: node-measured, statsd, ...
    • Analyze: Graphite, Librato Metrics, ...
    • Debug
    

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73. So if node doesn’t have magic
    scaling, what is it good for?
    

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74. 
    

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75. tl;dr
    • Know your requirements
    • There are no silver bullets
    

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76. Questions?
    Slides will be available at felixge.de
    

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77. Thanks
    

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78. Feedback
    

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