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This presentation was used for my thesis defense held at Universidad Politecnica de Catalunya, Spain, for a double-degree master programme in Distributed Computing. The other two universities participating in the programme are Royal Institute of Technology, Stockholm, Sweden and Instituto Tecnico Superior, Lisbon, Portugal.
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Thesis presentation:
Online recommendations at scale with matrix factorisation.
Royal Institute of Technology, Stockholm, SwedenInstituto Superior Técnico, Lisbon, PortugalUniversitat Politécnica de Catalunya, Barcelona, Spain
22 June 2012Marcus Ljungblad
75% of the 30 million daily movie starts are sourced from recommendations."
a key differentiating factor"
3 challenges
How do you serve recommendations from millions of items to millions of users online?
2 4 4 ? 13 5 ? ? 1? 4 2 1 ?
1 ? 1 3 3
Video ratingsU
sers
f( )
2.05 3.97 3.96 2.12 1.012.93 5.02 3.21 1.61 0.982.15 3.95 2.01 1.05 1.10 1.00 4.29 1.01 2.96 2.98
Video ratingsU
sers
2.05 3.97 3.96 2.12 1.012.93 5.02 3.21 1.61 0.982.15 3.95 2.01 1.05 1.10 1.00 4.29 1.01 2.96 2.98
Video ratings
Use
rs
2 4 4 ? 13 5 ? ? 1? 4 2 1 ?1 ? 1 3 3
2.05 3.97 3.96 2.12 1.012.93 5.02 3.21 1.61 0.982.15 3.95 2.01 1.05 1.10 1.00 4.29 1.01 2.96 2.98
13x40M I L L I O NR A T I N G S
Interface Delegate Router Worker
requeststart
route
compute
top-N
to jsonreply
merge
Interface Delegate Router Worker
requeststart
route
compute
top-N
to jsonreply
merge
Did it work?
Setup:
• 1-3 machines
• 1 million items
• same rack = high-speed
• 1 test machine
Performance!
Performance!
huh?!
Did it work?wel
l
74% = 74%Offline Online
Summary:
... clustering depends on data ...
... need balanced clusters ...
... memory bound ...
... scales ok ...
Thank you!
Photos and pictures borrowed from the Internetz:
Iron Maiden cover: http://en.wikipedia.org/wiki/File:Iron_Maiden_(album)_cover.jpgCat picture: http://www.lastfm.es/group/CatsCoins: http://www.sxc.hu/photo/1235540iPhones: http://blog.bayuamus.com/2011/08/user-experience-comparison-between-htc-salsa-and-samsung-galaxy-mini/Amazon recommendations: http://mashable.com/2010/08/06/online-retail-facebook-data/TV remote: http://www.flickr.com/photos/62337512@N00/2749561795/sizes/z/in/photostream/Headphones: http://www.flickr.com/photos/markusschoepke/82957375/sizes/m/in/photostream/Function: http://en.wikipedia.org/wiki/File:Graph_of_example_function.svgHome servers: http://www.flickr.com/photos/fabrico/477844434/sizes/z/in/photostream/
Extra material...
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