Dennis Dang dangdennis

Stevey's Google Platforms Rant

I was at Amazon for about six and a half years, and now I've been at Google for that long. One thing that struck me immediately about the two companies -- an impression that has been reinforced almost daily -- is that Amazon does everything wrong, and Google does everything right. Sure, it's a sweeping generalization, but a surprisingly accurate one. It's pretty crazy. There are probably a hundred or even two hundred different ways you can compare the two companies, and Google is superior in all but three of them, if I recall correctly. I actually did a spreadsheet at one point but Legal wouldn't let me show it to anyone, even though recruiting loved it.

I mean, just to give you a very brief taste: Amazon's recruiting process is fundamentally flawed by having teams hire for themselves, so their hiring bar is incredibly inconsistent across teams, despite various efforts they've made to level it out. And their operations are a mess; they don't real

Haskell vs Clojure

The JSON data is in the following format

{
    "Genesis": {
        "1": {
            "1": "In the beginning..." ,
            "2": "..."

Sans jQuery

Events

// jQuery
$(document).ready(function() {
  // code
})

MySQL

Getting started

Using OTP's observer (appmon replacement) remotely

$ ssh remote-host "epmd -names"
epmd: up and running on port 4369 with data:
name some_node at port 58769

Note the running on port for epmd itself and the port of the node you're interested in debugging. Reconnect to the remote host with these ports forwarded:

$ ssh -L 4369:localhost:4369 -L 58769:localhost:58769 remote-host

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics

elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent

	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

	/*
	* Reference:
	* http://www.quora.com/Computer-Programming/What-are-some-cool-bit-manipulation-tricks-hacks
	* http://www.catonmat.net/blog/low-level-bit-hacks-you-absolutely-must-know/
	*/

	#include <iostream>
	#include <string.h>

	using namespace std;

	import sys, os.path, hashlib, re
	import zipfile
	import subprocess
	from StringIO import StringIO
	from io import BytesIO

	#
	# Passbook Hack
	# David Schuetz
	# 30 May 2014

	// General hints on defining types with constraints or invariants
	//
	// Just as in C#, use a private constructor
	// and expose "factory" methods that enforce the constraints
	//
	// In F#, only classes can have private constructors with public members.
	//
	// If you want to use the record and DU types, the whole type becomes
	// private, which means that you also need to provide:
	// * a constructor function ("create").