GoRuCo2011 Notes

goruco_2011_notes.md

GoRuCo 2011 | Gordon Diggs

Ryan Smith (@ryandotsmith)

• Gene Amdahl's Law
• How to improve concurrency
  • Removing FIFO
    • FIFO isn't really needed a lot of the time in a queue of jobs
      • can ditch FIFO if order of jobs doesn't matter
      • if order matters, have a job fire things that depend on it at completion
    • fuzzy-FIFO
      • have many head nodes with a top boundary
      • worker can take job from any head node above top boundary
    • lock_head() (PL/pgSQL) EXECUTE 'SELECT id FROM' || ' jobs' || ' WHERE locked_at IS NULL' || ' ORDER BY id ASC' || ' LIMIT 1' || ' OFFSET' || relative_top || ' FOR UPDATE' || ' NOWAIT' INTO locked;
      • do this procedure with a spin lock
      • skip lock ?
    • MVCC
  • Relax constraints
• github.com/ryandotsmith/queue_classic
  • dependencies
    1. pg gem
    2. json
  • faster b/c it doesn't make a lot of object

Sandi Metz (@sandimetz)

• Code needs to work today just once, and be easy to change forever
• The purpose of design is to reduce the cost of change
• Simple ways to judge the goodness of code
  • Transparent - the consesquences of change are visible and predictable
  • Reasonalbe - the cost of adding a new feature is proportional to its value
  • Usable - if you wrote it, you can reuse it
  • Exemplary - More code like this would be good for your app
• Code will never be done, just need to know when to stop
• Slides: less-goruco.heroku.com
• Don't guess what changes will come, just guess what will change.
• Let objects stand free

Paul Dix (@pauldix)

• redis is single-threaded
• redis.pipelined
• ZeroMQ

Casey Rosenthal (@caseyrosenthal)

• github.com/clr
• 2K Bot Competition
• Pogamut - team actions?

Jeremy Ashkenas

• TextMate bundle to compile/run coffeescript
• altjs.org

Mat Brown (@0utoftime) & John Crepezzi (@seejohnrun)

• SQL Operators
  • Bulk inserts incredibly faster than regular inserts
  • HAVING count(1) > 1
  • Pagination
    • SELECT SQL_CALC_FOUND ROWS * FROM people WHERE face = 'awesome' LIMIT 10 OFFSET 20;
    • SELECT FOUND_ROWS();
• slim_scrooge github.com/sdskyes/slim_scrooge
  • Learns to select only what's necessary
  • Uses a lot of memory for bigger apps
• String Operators: strlen, left, right, concat, reverse
• DB regex: SELECT 'John' REGEXP '^[a-zA-Z]+$';
• Think about setting max lengths for fields - could save a lot of space at scale
• validates_uniqueness_of doesn't work.
  • :unique is property of index, not column
• github.com/seejohnrun/database_validation
• ENUMs - kind of like validates_inclusion_of
  • pg adapter doesn't absoultely support - but gems exist to do so
• Single Table Inheritance
  • if subclasses differ only in behavior, ok
  • otherwise, use Class-Table Inheritance
    • Superclass table stores common attributes
    • Not supported by ActiveRecord

Evan Phoenix (@evanphx)

• Sleep is invisible in run times except real
• Huge real time may indicate blocking as well
• gist.github.com/1008305
• community@rubini.us for shirts

githits.me/NewYorkCity

Lua

NIce Gordon!