JS and Parallel Processing(!?)

by Joe Karlsson

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@JoeKarlsson1 ! 1 JS + Parallel Processing(!?) www.joekarlsson.com

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@JoeKarlsson1 ! 2 Joe Karlsson @JOEKARLSSON1 @JOEKARLSSON JOEKARLSSON.COM

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@JoeKarlsson1 ! 3 How is this going to work?

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@JoeKarlsson1 ! 4 JavaScript was designed to run on a single thread

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@JoeKarlsson1 ! 5 Can Do Anything Multithreads Can do Easy to Program Easy to Port Code *For non-data intensive operations *Faster Than Multithreads Easy to Debug/Test Why Single Threads?

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@JoeKarlsson1 ! 6 What’s the problem?

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@JoeKarlsson1 ! 7

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@JoeKarlsson1 ! 8 Single thread is SHARED with the browser

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@JoeKarlsson1 ! 10 • Parsing large JSON set • Image Processing • Sound Processing • Real Time Analytics Things that take a lot of time

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@JoeKarlsson1 ! 11

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@JoeKarlsson1

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@JoeKarlsson1 ! 13 This even is worse on mobile

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@JoeKarlsson1 ! 14 So, how do we deal with slow processes?

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@JoeKarlsson1 ! 15 We could send the CPU intense process to a server

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@JoeKarlsson1 ! 16

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@JoeKarlsson1 ! 17 Web Workers Multiple Threads in the browser!

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@JoeKarlsson1 ! 18 Background scripts that run on a different thread

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@JoeKarlsson1 ! 19 • Faster • More Responsive • Battery efficient • Support in every major browser (IE 10+)

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@JoeKarlsson1 ! 20 Web Workers cannot directly access the Window Object or the DOM

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@JoeKarlsson1 ! 21 How do Web Workers work?

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@JoeKarlsson1 ! 22

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@JoeKarlsson1 ! 23 Each Web Worker you create === a new thread

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@JoeKarlsson1 ! 24

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@JoeKarlsson1 ! 25 They communicate via Message Channel

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@JoeKarlsson1 ! 27 Web Workers operate in a different context They cannot directly access the Window or DOM

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@JoeKarlsson1 ! 28 But they can do pretty much everything else the main thread can do

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@JoeKarlsson1 ! 29 Let’s look at real code Code: https://github.com/JoeKarlsson/live-code/tree/master/web-workers

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@JoeKarlsson1 ! 34 /js/bigLoop.js

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@JoeKarlsson1 ! 36 How do we stop a Web Worker?

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@JoeKarlsson1 ! 40 Errors?

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@JoeKarlsson1 ! 41 js errror

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@JoeKarlsson1 ! 43 How to check for browser support?

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@JoeKarlsson1 ! 44 browser

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@JoeKarlsson1 ! 46 Future of Web Workers

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@JoeKarlsson1 ! 48 WebGL and Canvas2D

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@JoeKarlsson1 ! 51 • Web Workers are relatively heavy- weight, and are not intended to be used in large numbers • Web Workers are amazing but hard to manage

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@JoeKarlsson1 ! 52 Questions ?

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@JoeKarlsson1 ! 53 Thank You!

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@JoeKarlsson1 ! 54 Let’s Stay In Touch @JOEKARLSSON1 @JOEKARLSSON JOEKARLSSON.COM

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@JoeKarlsson1 ! 55 Additional Resources 1. Code: https://github.com/JoeKarlsson/live-code/tree/master/web-workers 2. Slides: 3. Web Workers: https://developer.mozilla.org/en-US/docs/Web/API/ Web_Workers_API/Functions_and_classes_available_to_workers  4. Web Workers: http://techslides.com/html5-web-workers-for-ajax-requests  5. Workers: https://html.spec.whatwg.org/multipage/workers.html#shared- workers-introduction

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@JoeKarlsson1 ! 56