NodePDX Slides
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This document discusses building MapAttack, a real-time geolocation game, and describes some issues encountered with the initial implementation. It provides an overview of how Geoloqi was used to address problems with server blocking, concurrent traffic, and asynchronous processing. Advice is also given on database performance and scaling through approaches like caching frequently used data and using high-performance hardware.
NodePDX Slides
- 1. Building MapAttack: A real-time geolocation game Kyle Drake Sunday, February 12, 12
- 2. geoloqi.com What is Geoloqi? geoloqi.com Sunday, February 12, 12
- 3. geoloqi.com Real-world solutions for thousands around the globe Sunday, February 12, 12
- 4. geoloqi.com Real-Time Location Tracking Real-World Interactive Experiences Sunday, February 12, 12
- 5. geoloqi.com Personal Location Sunday, February 12, 12
- 6. geoloqi.com Location-Based Notes Sunday, February 12, 12
- 7. geoloqi.com YOUR GPS GETS WEIRD. WE HELP FIX THAT. Sunday, February 12, 12
- 8. geoloqi.com Real-Time Applications Sunday, February 12, 12
- 10. geoloqi.com First Hackathon Attempt Layer in Geoloqi Updates to MapAttack server via HTTP REST API Processing through Geoloqi’s persistent store Finished in a weekend A lot of fun! Sunday, February 12, 12
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- 15. geoloqi.com There were some kinks Used an REST HTTP service for APNS (worked, but not “real-time”) Server was getting backed up (updates were not async) Sunday, February 12, 12
- 16. geoloqi.com MapAttack Server Issues Blocking IO (requests to Geoloqi API held everything up) Lots of concurrent traffic Events had to be broadcast to all phones/ clients in the game synchronously Sunday, February 12, 12
- 17. geoloqi.com HOW WE DEALT WITH IT Sunday, February 12, 12
- 19. geoloqi.com A key-value store, and so much more A great implementation of PUBLISH/SUBSCRIBE So simple, you can actually understand it Very fast and reliable Robust library support Sunday, February 12, 12
- 24. geoloqi.com HOW WE USE NODE JS • Phones: Custom binary protocol over UDP • Web Browsers: Web Sockets via Socket.IO Sunday, February 12, 12
- 25. geoloqi.com Socket.IO is awesome Adapter Pattern for realtime Web Sockets, Flash, Long Polling! One interface for everything Easy to implement: ~100 LOC Sunday, February 12, 12
- 27. geoloqi.com Geoloqi API ASYNC FTW! Delayed updates when possible Messages queues: Beanstalk Workers pick tasks off the stack Process data outside of the persistent store Simpler than AMQP Sunday, February 12, 12
- 29. geoloqi.com The Reactor Pattern “The reactor design pattern is a concurrent programming pattern for handling service requests delivered concurrently to a service handler by one or more inputs” - Wikipedia My simplest description: Takes your blocking IO operation, shoves it into its own kernel thread behind the scenes, uses Unix kernel magic to make it rejoin the reactor queue when it’s ready. Linux: epoll(4) BSD: kqueue/kevent Sunday, February 12, 12
- 30. geoloqi.com Concurrent IO is a common problem All programming languages have trouble with it The Reactor pattern is a tool to resolve it Most languages have the Reactor pattern! JavaScript Node.js Python Twisted Ruby EventMachine (libem, C) Java JBoss_Netty PHP None yet Sunday, February 12, 12
- 31. geoloqi.com MapAttack Server (or: How to make Ruby ROFLscale) MRI Ruby has a global interpreter lock But MRI Ruby does not block on IO JRuby and Rubinius 2: Native Threads And it has a reactor pattern, just like Node JS Sunday, February 12, 12
- 32. geoloqi.com Sinatra::Synchrony kyledrake.net/sinatra-synchrony Implements EventMachine with Fibers The result: NO CALLBACKS < 100 LOC Only coding change is to use EM libs and fibers DON’T USE IT. Sunday, February 12, 12
- 33. geoloqi.com Sinatra::Synchrony Sunday, February 12, 12
- 35. geoloqi.com Let’s Talk Performance. Sunday, February 12, 12
- 36. geoloqi.com Database = your real persistence problem Sunday, February 12, 12
- 37. geoloqi.com Make the relevant data stay outside of the slow persistence store. Sunday, February 12, 12
- 38. geoloqi.com If you’re trying to solve a problem by ROFLscaling your persistent store, you’re doing it wrong. Sunday, February 12, 12
- 39. geoloqi.com Examples of doing it wrong “Let’s rewrite everything to use TrendDB” Using EC2 for a single-master DB “because it scales” Buying something from Oracle “Ruby/PHP/JS is too slow for this, let’s rewrite it in TrendLang” Many NoSQL solutions have problems you don’t know about. Global write locks, single write master, et cetera Sunday, February 12, 12
- 40. geoloqi.com If you must speed up your persistent store, here’s my practical advice. Sunday, February 12, 12
- 41. geoloqi.com Real Hardware FTW? Single master database? Get a real server! Really! Cloud is only as fast as the fastest available HDD EBS performance is not great, even in RAID0 stripe See orion.heroku.com/past/2009/7/29/io_performance_on_ebs and perfcap.blogspot.com/2011/03/understanding-and-using-amazon-ebs.html and blog.dt.org/index.php/2010/06/amazon-ec2-io-performance-local-emphemeral-disks-vs-raid0- striped-ebs-volumes/ and endevver.com/2010/03/cost-analysis-of-an-amazon-ec2-deployment.html and mysqlperformanceblog.com/2011/02/21/death-match-ebs-versus-ssd-price-performance-and- qos and google.com/search?q=heroku+ebs+performance High end Xeon, 32GB ECC, fast 220GB SSD: ~$2K Sunday, February 12, 12
- 42. geoloqi.com Real Hardware FTW? The paradigm is diversifying, and the reason is SSD. Say hello to the Fusion-io ioDrive Octal. PCIe x16 slot 5.12TB 6.0 GB/s read 4.4 GB/s write 1.19 MILLION IOPS Cost: $100,000 (plus $10 S&H). It’s a steal at this price.. but it will get cheaper. Sunday, February 12, 12
- 43. geoloqi.com Real Hardware FTW? $500 PCIe SSD drives: 220GB >100,000 IOPS ~700MB/s R/W 15,000 RPM SAS drives: 2TB+ ~175-210 IOPS <150MB/s R/W Sunday, February 12, 12
- 44. geoloqi.com Long Term Multi-master experiment (Brewer’s CAP) Riak is my current favorite Cloud companies providing real hardware performance Map/Reduce != Database Sunday, February 12, 12
- 45. geoloqi.com In Summary Sunday, February 12, 12
- 46. geoloqi.com Geo-location games are FUN! Sunday, February 12, 12
- 47. geoloqi.com Use the Geoloqi API to make geolocation games! We did the hard work for you. Sunday, February 12, 12
- 48. geoloqi.com MapAttack is open source! github.com/geoloqi/MapAttack Sunday, February 12, 12
- 49. geoloqi.com Other uses of Geoloqi Sunday, February 12, 12
- 50. geoloqi.com Thanks! Sunday, February 12, 12