michalbcz

NDJSON is a convenient format for storing or streaming structured data that may be processed one record at a time.

• Each line is a valid JSON value
• Line separator is ‘\n’

1. Convert JSON to NDJSON?

cat test.json | jq -c '.[]' > testNDJSON.json

michalbcz

"use strict";

var API_KEY = '__API_KEY__';
var PHOTOSET_IDS = ['__ID1__', '__ID2__', '__ID3__'];

var cartagenaApp = angular.module('cartagenaApp');

cartagenaApp.directive('flickrBackground', function(Flickr, $http) {
    var _flickrBackground = function($scope, $element) {
      var nextPhoto;

michalbcz

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

michalbcz

    private void test(List<ExchangeRate> exchangeRates) {
        Map<String, ExchangeRate> rateType11Map = new HashMap<String, ExchangeRate>();
        Map<String, ExchangeRate> rateType12Map = new HashMap<String, ExchangeRate>();

        Collections.sort(exchangeRates, new Comparator<ExchangeRate>() {
            @Override
            public int compare(ExchangeRate e1, ExchangeRate e2) {
                return ComparisonChain.start()
                        .compare(e1.getRateCurrency(), e2.getRateCurrency())
                        .compare(e1.getRateType(), e2.getRateType())

michalbcz

 def generateMD5(String s) {
    MessageDigest digest = MessageDigest.getInstance("MD5")
    digest.update(s.bytes);
    new BigInteger(1, digest.digest()).toString(16).padLeft(32, '0')
 } 

michalbcz

Latency Comparison Numbers
--------------------------
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
Send 1K bytes over 1 Gbps network        10,000   ns    0.01 ms
Read 4K randomly from SSD*              150,000   ns    0.15 ms