Damian Gryski dgryski

Internet Scale Services Checklist

A checklist for designing and developing internet scale services, inspired by James Hamilton's 2007 paper "On Desgining and Deploying Internet-Scale Services."

http://mvdirona.com/jrh/talksandpapers/jamesrh_lisa.pdf

Basic tenets

Does the design expect failures to happen regularly and handle them gracefully?
Have we kept things as simple as possible?

Description

This simple script will take a picture of a whiteboard and use parts of the ImageMagick library with sane defaults to clean it up tremendously.

The script is here:

#!/bin/bash
convert "$1" -morphology Convolve DoG:15,100,0 -negate -normalize -blur 0x1 -channel RBG -level 60%,91%,0.1 "$2"

Results

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

General Background and Overview

Probabilistic Data Structures for Web Analytics and Data Mining : A great overview of the space of probabilistic data structures and how they are used in approximation algorithm implementation.
Models and Issues in Data Stream Systems
Philippe Flajolet’s contribution to streaming algorithms : A presentation by Jérémie Lumbroso that visits some of the hostorical perspectives and how it all began with Flajolet
Approximate Frequency Counts over Data Streams by Gurmeet Singh Manku & Rajeev Motwani : One of the early papers on the subject.
[Methods for Finding Frequent Items in Data Streams](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.187.9800&rep=rep1&t

	* {
	font-size: 12pt;
	font-family: monospace;
	font-weight: normal;
	font-style: normal;
	text-decoration: none;
	color: black;
	cursor: default;
	}

	# add this code to your .bashrc file

	# gitpending() transverses from the current directory to
	# inspect 1 directory level deep for any git repos that have
	# pending changes to commit.
	function gitpending()
	{
	for d in */ ; do
	pushd $d > /dev/null
	DIRNAME=$(basename "$d")

	// Process github event data exports.
	//
	// Go here for more info: http://www.githubarchive.org/
	package main

	import (
	"compress/gzip"
	"encoding/csv"
	"encoding/json"
	"io"

	ace.require("ace/lib/net").loadScript("https://raw.github.com/ajaxorg/ace-builds/master/src-min-noconflict/keybinding-vim.js", function() {
	e = document.getElementById("ace-editor").env.editor;
	e.setKeyboardHandler(ace.require("ace/keyboard/vim").handler);
	})

	" returns a string <branch/XX> where XX corresponds to the git status
	" (for example "<master/ M>")
	function CurrentGitStatus()
	let gitoutput = split(system('git status --porcelain -b '.shellescape(expand('%')).' 2>/dev/null'),'\n')
	if len(gitoutput) > 0
	let b:gitstatus = strpart(get(gitoutput,0,''),3) . '/' . strpart(get(gitoutput,1,' '),0,2)
	else
	let b:gitstatus = ''
	endif
	endfunc