Post on 15-Jan-2015
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Mihai Oaida
Senior Web Developer @ www.imobiliare.roStudent , Politehnica Timi oarașWeb technologies instructor
www.tehnologii-web.ro
Scaling Web Applications
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We will talk about ...
FactsTheory + Myths ArchitectureStatic contentDynamic contentCaching
Scaling Web Applications
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Web application facts
Mostly stateless Very read intensive ( > 90% )Not so dynamicCan be fine grained
Highly scalable, if designed to :)
Scaling Web Applications
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Hardware facts
Limited context switchingLimited opened filesVery limited random IO Limited sequential IOLimited RAM
Scaling Web Applications
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Scalability vs Performance
Scalability how many
Performancehow fast
Scalability + Performance how many and how fast
Scaling Web Applications
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Vertical vs Horizontal
Vertical Scaling Bigger server2X capacity != 2x price
Horizontal ScalingMore identical servers 2X capacity ≈ 2x price
Scaling Web Applications
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Benchmarking and Profiling
Benchmarking How fast a page loads, under certain
conditions
ProfilingIn a page execution, how much time each
component consumes
Scaling Web Applications
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Benchmarking and Profiling
Benchmarking Page / site performance?Page / site scalability ?
ProfilingWhat is the bottleneck?
Scaling Web Applications
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Benchmarking and Profiling
Prepare testsExpect resultsRun repeatable testsAnalyse dataInterpret data correctly !!!
Scaling Web Applications
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Architecture
Web server – dynamic, static contentDatabase serverCaching server
+ load balancer+ network equipment
Scaling Web Applications
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Static content - HTTP optimization
Use Expires and Last-Modified headersUse sprites for imagesMerge css filesMerge js filesUse compression – gzipUse multiple subdomains
img1.tehnologii-web.ro img2.tehnologii-web.ro
Scaling Web Applications
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Static content - Server
Use dedicated server(s) just for staticUse asynchronous web servers
Lighthttpd, nginx
Or,Just use a CDN ( Content delivery network )
Scaling Web Applications
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Dynamic content
Usually web servers are not the bottleneck
Code optimizationUse less RAM and less CPUgood performance!= good scalability
For PHPOpcode cache : xCache, apc, eAccelarator
Scaling Web Applications
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Dynamic content
Dynamic = 0.x% static + 0.y% dynamic ?
Can real-time data have a 5 minute delay ?
Batch writesPre-cache
Scaling Web Applications
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Database - general
Choose an open-source one that has proven to scale: MySQL :)
Use Master – Slave architectureWrite on master(s)Read from slaves
Scaling Web Applications
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Database
Don't run on the default configuration
key_buffer, query cache, sort buffer, etc
All need tuning as data changes
Scaling Web Applications
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Database
Use indexes – don't index everythingCreate very selective indexes, high cardinalityJoin tables very carefullyDenormalize
Scaling Web Applications
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Database
Optimize queriesUse DESCRIBE commandActivate slow query log and monitor it!
Scaling Web Applications
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Cache - Memcache
Asynchronous serverNo authenticationKey value databaseIn memoryVery scalableHas api in many languagesSmall limitations
Scaling Web Applications
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Conclusions
There is no secret recipe, no easy solutionIt is very application specific
To scale you need not only the right tools but the right thinking!
Scaling Web Applications
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