Jeyan Burns-Oorjitham jeyoor

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

[**Please, don't use `mysql_*` functions in new code**](http://bit.ly/phpmsql). They are no longer maintained [and are officially deprecated](http://j.mp/XqV7Lp). See the [**red box**](http://j.mp/Te9zIL)? Learn about [*prepared statements*](http://j.mp/T9hLWi) instead, and use [PDO](http://php.net/pdo) or [MySQLi](http://php.net/mysqli) - [this article](http://j.mp/QEx8IB) will help you decide which. If you choose PDO, [here is a good tutorial](http://j.mp/PoWehJ).

Please, don't use mysql_* functions in new code. They are no longer maintained and are officially deprecated. See the red box? Learn about prepared statements instead, and use PDO or MySQLi - this article will help you decide which. If you choose PDO, here is a good tutorial.

The introduction to Reactive Programming you've been missing

(by @andrestaltz)

This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

#Container Resource Allocation Options in docker-run

now see: https://docs.docker.com/engine/reference/run/#runtime-constraints-on-resources

You have various options for controlling resources (cpu, memory, disk) in docker. These are principally via the docker-run command options.

##Dynamic CPU Allocation -c, --cpu-shares=0
CPU shares (relative weight, specify some numeric value which is used to allocate relative cpu share)

READ FIRST

This is outdated information, though the concepts are valid. A script implmenting these concepts for OpenConnect 8 on Ubuntu 18 (bionic) and 19 (eoan) is available

Building OpenConnect 7 on Ubuntu 14 (trusty) and 15 (vivid)

The steps in this guide are available as an autobuild shell script

	;;
	;; NS CHEATSHEET
	;;
	;; * :require makes functions available with a namespace prefix
	;; and optionally can refer functions to the current ns.
	;;
	;; * :import refers Java classes to the current namespace.
	;;
	;; * :refer-clojure affects availability of built-in (clojure.core)
	;; functions.

	-- http://richarddingwall.name/2008/12/21/find-missing-foreignprimary-keys-in-sql-server/

	-- Find columns on tables with names like FooID or FooCode which should
	-- be part of primary or foreign keys, but aren't.
	SELECT
	t.name AS [Table],
	c.name AS [Column],
	i.*
	FROM
	sys.tables t

	-- \|A list of `Range's. This is the comprehensive ref type, and
	-- can form an arbitrarily complex reference to the scripture.

	data Reference = Reference [Range] -- [ x ] means list of x's
	deriving (Show, Eq)

	-- \|A Range of verses, or a single ref. "Range" is a bit of a misnomer,
	-- since we can have a single reference "Range".
	data Range
	= Range

	import java.util.Set;
	import java.util.concurrent.ConcurrentHashMap;

	public class HelloCovariance {
	public static void main(String[] args) {
	ConcurrentHashMap<String, String> properties = new ConcurrentHashMap<>();
	Set<String> keySet = properties.keySet();
	}
	}