techtalk#6: nodejs: pitfalls (based on game project)

{Node.JS} Common pitfalls ( The story of small Game Development Project )

Agenda

• Event Loop, Non-Blocking I/O, Async Development • Debugging• Lessons learned, lessons forgotten• Born to Scale (Scalability in mind)• Hey going to production!! Oooops ….

Event LoopSingle Thread – one global scope

Async Development – Burn in Hell

Async Development – Callback Hell ResolvingGive the names to your callbacks

Async Development – Callback Hell ResolvingDivide your structure to small functions

Async Development – Callback Hell ResolvingPromises

Debugging

WebStorm IDE Debugger›Node-Inspector module

Lessons learned, lessons forgotten (Development Phase)

• Choose framework you know or used in previous projects• Don't forget to clear the timer once you set it – or the magic will happen in your app• Divide the code to modules and classes – from beginning• Bot is the same as the user – unification for clarity• Don't use multistep CSS3 animation – you will need to have “animation finished” event• Don't start full refactoring – you will loose a time and will through this idea soon• Use class constants instead of magic numbers 0,1,2 …• Put conditions into functions

Born to Scale (Scalability In mind)

• One way – store application state in cache or db Then put the NodeJs behind the reverse proxy like Nginx• Another way – split socket.io connections across servers + use so called “sticky sessions”

Hey going to production!! Oooops ….

• Logging – log more, log early• Forget about debugger• Who will up your server when it's down - “Forever”• Exceptions - don't throw them until you catch them• Load Balancing – Nginx as reverse Proxy• One thread – one CPU core – Use cluster module

Links

http://strongloop.com/strongblog/node-js-callback-hell-promises-generators/http://callbackhell.com/https://github.com/nodejitsu/foreverhttp://nodejs.org/docs/v0.6.0/api/cluster.htmlhttp://blog.keithcirkel.co.uk/load-balancing-node-js/