hellerbarde

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
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

jboner

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
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 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

karpathy

"""
Minimal character-level Vanilla RNN model. Written by Andrej Karpathy (@karpathy)
BSD License
"""
import numpy as np

# data I/O
data = open('input.txt', 'r').read() # should be simple plain text file
chars = list(set(data))
data_size, vocab_size = len(data), len(chars)

zhengjia

=Navigating=
    visit('/projects')
    visit(post_comments_path(post))

=Clicking links and buttons=
    click_link('id-of-link')
    click_link('Link Text')
    click_button('Save')
    click('Link Text') # Click either a link or a button
    click('Button Value')

isaacbowen

# config/initializers/will_paginate.rb

module WillPaginate
  module ActionView
    def will_paginate(collection = nil, options = {})
      options[:renderer] ||= BootstrapLinkRenderer
      super.try :html_safe
    end

    class BootstrapLinkRenderer < LinkRenderer

keis

import asyncio

@asyncio.coroutine
def waiting(r):
    print("hello from waiting -", r)
    yield from asyncio.sleep(2)
    print("bye from waiting -", r)
    return r

jamesgary

Dissecting Ruby with Ruby

Richard Schneeman (@schneems)

• Get into a library
  • bundle open wicked
  • Make sure you've set your $EDITOR
• Forget fancy debuggers
  • All you need is puts
  • A rubyist's tracer round: puts "================="
• Notation