Terje Sten Bjerkseth terjesb

EuroClojure 2014, Krakow

Fergal Byrne, Clortex: Machine Intelligence based on Jeff Hawkins’ HTM Theory

@fergbyrne
HTM = Hierarchical Temporal Memory
Slides

big data

big data is like teenage sex
- noone knows how to do it
- everyone thinks everyone else is doing it

Magento Enterprise 1.12 cluster

Scaling Magento presentation with 60 slides and notes, which was then reviewed by Alan Storm.

One of the best ways to reduce complexity (read: stress) in web development is to minimize the differences between your development and production environments. After being frustrated by attempts to unify the approach to SSL on my local machine and in production, I searched for a workflow that would make the protocol invisible to me between all environments.

Most workflows make the following compromises:

Use HTTPS in production but HTTP locally. This is annoying because it makes the environments inconsistent, and the protocol choices leak up into the stack. For example, your web application needs to understand the underlying protocol when using the secure flag for cookies. If you don't get this right, your HTTP development server won't be able to read the cookies it writes, or worse, your HTTPS production server could pass sensitive cookies over an insecure connection.
Use production SSL certificates locally. This is annoying

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

	(ns n01se.externs-for-cljs
	(:require [clojure.java.io :as io]
	[cljs.compiler :as comp]
	[cljs.analyzer :as ana]))

	(defn read-file [file]
	(let [eof (Object.)]
	(with-open [stream (clojure.lang.LineNumberingPushbackReader. (io/reader file))]
	(vec (take-while #(not= % eof)
	(repeatedly #(read stream false eof)))))))

	;;; show-your-colours --- an HTTP server showing the current buffer fontified

	;; Author: Wilfred Hughes <[email protected]>
	;; Version: 0.1
	;; Package-Requires: ((s "1.3.0"))

	;;; Commentary:

	;; Allow others to see what you're editing in Emacs. For live
	;; screencasts, or general Emacs advocacy. If you have multiple

	(defmacro test->
	"Takes an expression and a set of test/form pairs. Threads expr (via ->)
	through each form for which the corresponding test expression (not threaded) is true."
	[expr
	& clauses]
	(assert (even? (count clauses)))
	(let [g (gensym)
	pstep (fn [[test step]] `(if ~test (-> ~g ~step) ~g))]
	`(let [~g ~expr
	~@(interleave (repeat g) (map pstep (partition 2 clauses)))]

	(use '[datomic.api :only (q db) :as d])

	(def initial-data
	[{:sku "1" :price 0.95M :qty 1}
	{:sku "2" :price 1.99M :qty 0}
	{:sku "3" :price 1.99M :qty 0}
	{:sku "4" :price 5.99M :qty 3}
	{:sku "5" :price 9.99M :qty 2}
	{:sku "6" :price 2.99M :qty 3}
	{:sku "7" :price 2.99M :qty 2}])

	(ns datomic-helpers
	(:require [datomic.api :as d]))

	;;; Expose Datomic vars here, for convenience

	;;; Ring middleware

	(defn wrap-datomic
	"A Ring middleware that provides a request-consistent database connection and
	value for the life of a request."