Volodymyr Pavlenko pavlenko-volodymyr

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

Clarify and agree on the scope of the system

User cases (description of sequences of events that, taken together, lead to a system doing something useful)
- Who is going to use it?
- How are they going to use it?

Proposed levels of skill for the scala programming language, can be used as a base for a curriculum

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

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

	public class Main {
	private static long test(long max) {
	long sum = 0;
	for (int i = 0; i < max; i++) {
	for (int j = i; j > 0; j--) {
	sum += j % 10 + j / 10;
	}
	}
	return sum;
	}

	package main

	import (
	"fmt"
	"math/rand"
	"time"
	)

	func SumAll(max int) int64 {
	var sum int64

	def min_marriage_age(age):
	pass

	@min_marriage_age(22)
	class Person:
	first_name: str
	last_name: str
	age: int
	min_age: int

	const http = require('http')
	const { Pool } = require('pg')

	const pool = new Pool({
	user: '',
	database: 'bigint',
	password: '',
	})

	#!/bin/sh

	MESOS_HOME="/tmp/mesos"

	cd "$(\ls -1dt $MESOS_HOME/slaves/*/ \| head -n 1)" && \
	cd "$(\ls -1dt frameworks/*/ \| head -n 1)" && \
	cd executors/atropos-executor/runs/latest

	7z
	abw
	ai
	bmp
	cab
	cr2
	csv
	djvu
	doc
	docx