sahilsk

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns                     on recent CPU
L2 cache reference ........................... 7 ns                     14x L1 cache
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns                     20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs 4X memory

sahilsk

# == Schema Information
#
# Table name: tasks
#
#  id                  :integer          not null, primary key
#  date                :date
#  task                :text
#  tid                 :string(255)
#  actual_time_taken   :float
#  billable_time_taken :float

sahilsk

if (typeof window.localStorage == 'undefined' || typeof window.sessionStorage == 'undefined') (function () {

var Storage = function (type) {
  function createCookie(name, value, days) {
    var date, expires;

    if (days) {
      date = new Date();
      date.setTime(date.getTime()+(days*24*60*60*1000));
      expires = "; expires="+date.toGMTString();

sahilsk

db.campaigns.find(
   {
     target_region :
       { $near :
          {
            $geometry: { type: "Point",  coordinates: [-80.190262, 25.774252] },
            $maxDistance: 50000000
          }
       }
   }

sahilsk

curl -s https://api.github.com/orgs/twitter/repos?per_page=200 | ruby -rubygems -e 'require "json"; JSON.load(STDIN.read).each { |repo| %x[git clone #{repo["ssh_url"]} ]}'

sahilsk

curl -s https://api.github.com/orgs/twitter/repos?per_page=200 | ruby -rubygems -e 'require "json"; JSON.load(STDIN.read).each { |repo| %x[git clone #{repo["ssh_url"]} ]}'

sahilsk

//Example Usage

var seeker1 = function(msg) {
  console.log("seeker1 called: " + msg);
}

var seeker2 = function(msg) {
  console.log("seeker2 called: " + msg);
}

sahilsk

#!/bin/sh
#
# chkconfig: 2345 55 25
# Description: Nginx init.d script, put in /etc/init.d, chmod +x /etc/init.d/nginx
#              For Debian, run: update-rc.d -f nginx defaults
#              For CentOS, run: chkconfig --add nginx
#
### BEGIN INIT INFO
# Provides:          nginx
# Required-Start:    $all

sahilsk

# config/unicorn.rb
worker_processes Integer(ENV["WEB_CONCURRENCY"] || 3)
timeout 15
preload_app true

before_fork do |server, worker|
  Signal.trap 'TERM' do
    puts 'Unicorn master intercepting TERM and sending myself QUIT instead'
    Process.kill 'QUIT', Process.pid
  end

sahilsk

cheat sheet - simply copy-paste

Prerequisites

• virtualbox download
• vagrant download

Google Campus Tel-Aviv

• WiFi is Campus-Guest password is Elc0Campus

bootstrap