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

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

zziuni

# source : http://code.google.com/p/natvpn/source/browse/trunk/stun_server_list
# A list of available STUN server.

stun.l.google.com:19302
stun1.l.google.com:19302
stun2.l.google.com:19302
stun3.l.google.com:19302
stun4.l.google.com:19302
stun01.sipphone.com
stun.ekiga.net

deltamobile

package main

import (
        "fmt"
        "runtime"
        "time"
)

type Foo struct {
        name    string

panzi

#include <stdio.h>
#include <complex.h>
#define dc double complex
                                         dc
                                         Y(dc
                                           V,
                                      dc B,dc c){
                                        return
                               (cabs (V)<6)?(c?Y(V   *V+
                                 B,B,c-1):c):(2+c-4*cpow

cbednarski

import cv2

# Windows dependencies
# - Python 2.7.6: http://www.python.org/download/
# - OpenCV: http://opencv.org/
# - Numpy -- get numpy from here because the official builds don't support x64:
#   http://www.lfd.uci.edu/~gohlke/pythonlibs/#numpy

# Mac Dependencies
# - brew install python

tsiege

ANNOUNCEMENT

I have moved this over to the Tech Interview Cheat Sheet Repo and has been expanded and even has code challenges you can run and practice against!






\

kimenye

<?xml version="1.0" encoding="utf-8"?>
<manifest  xmlns:android="http://schemas.android.com/apk/res/android"
 android:versionCode="48513" android:versionName="2.11.301" package="com.whatsapp">
	<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION">
	</uses-permission>
	<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION">
	</uses-permission>
	<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE">
	</uses-permission>
	<uses-permission android:name="android.permission.ACCESS_WIFI_STATE">

keithshep

#!/usr/bin/env python -O

import argparse
import sys
import numpy
import h5py
import csv

class ColType:
    UNKNOWN = 1

lavalamp

There are three easy to make mistakes in go. I present them here in the way they are often found in the wild, not in the way that is easiest to understand.

All three of these mistakes have been made in Kubernetes code, getting past code review at least once each that I know of.

1. Loop variables are scoped outside the loop.

What do these lines do? Make predictions and then scroll down.

func print(pi *int) { fmt.Println(*pi) }