Golang 101 (Concurrency vs Parallelism)

fmt.Printf(“Hello, UNSADA”)

Pramesti Hatta K.
Software Engineer @Tech in Asia

Making things look hard is easy. Making hard
things look easy, that’s hard.

Meet Gopher, the funniest programming
language mascot.

2 types of programming language
compiled | interpreted

compiled languages are converted directly into
machine code

In contrast to compiled languages, interpreted
languages do not require machine code in order to
execute the program; instead, interpreters will
run through a program line by line and execute
each command.

compiled
● often faster execution
time
● often slower development
time
C/C++, Go, Fortran, Pascal
etc
interpreted
● often slower execution
time
● often faster development
time
PHP, Python, Ruby, JavaScript

statically typed
package main
import “fmt”
func main() {
var person string
person = “Maudy Ayunda”
fmt.Println(person)
person = 22
fmt.Println(person)
}
Output:
cannot use 22 (type int) as type
string in assignment
dynamically typed
<?php
$person = “Maudy Ayunda”;
echo $person;
$person = 22;
Echo $person;
Output:
Maudy Ayunda
22

Robert Griesemer, Rob Pike and Ken
Thompson

Go was born out of frustration with existing
languages and environments for systems
programming.

one had to choose either efficient compilation,
efficient execution, or ease of programming

programmers who could were choosing ease over
safety and efficiency by moving to dynamically
typed languages such as Python and JavaScript
rather than C++ or, to a lesser extent, Java.

Go is an attempt to combine the ease of
programming of an interpreted, dynamically typed
language with the efficiency and safety of a
statically typed, compiled language.

designed by Google to solve Google’s
problem.

Big software
● C++ (mostly) for servers, plus lots of java
and python
● thousands of engineers
● gazillions of lines of code

development at Google can be slow,
often clumsy.

Goals
● eliminate slowness
● eliminate clumsiness
● improve effectiveness

Go’s purpose is not research into
programming language design

Go’s purpose is to make software
engineer’s lives better.

Go Programming Language
● open source
● concurrent
● garbage collected
● efficient
● simple
● fun
● boring (to some)
https://golang.org

Go is a statically typed compiled
language.

Golang is a simple language. It has only 25 keywords.

Go keywords
break default func interface select
case defer go map struct
chan else goto package switch
const fallthrough if range type
continue for import return var

Yea I’m ready to learn this language

Basic structure
1.package main
2.
3.import “fmt”
4.
5.func main() {
6. fmt.Printf(“Hello, world.n”)
7.}

Package
1.package main
2.
3.import (
4. “fmt”
5. “math/rand”
6.)
7.
8.func main() {

Function
1.package main
2. …
3.func add(x int, y int) int
{
4. return x + y
5.}
6.
7.func main() {
Output
30

Function with multiple return
1.package main
2. …
3.func swap(x, y string) (string, string)
{
4. return y, x
5.}
6.
7.func main() {
Output
world hello

Variables
1.package main
2. …
3.var x int
4.
5.func main() {
6. var y string
7. y = "Hi!"
8. fmt.Println(y)
Output
Hi!
0

Short declaration variables
1.package main
2. …
3.
4.func main() {
5. y := “Hi!”
6. fmt.Println(y)
7.}
Output
Hi!

Basic types
bool
string
int int8 int16 int32 int64
uint uint8 uint16 uint32 uint64 uintptr
byte // alias for uint8
rune // alias for int32
float32 float64
complex64 complex128

Looping
1.package main
2. …
3.
4.func main() {
5. for i := 1; i <= 10; i++ {
6. fmt.Println(i)
7. }
Output
1
2
3
4
5
6
7
8
9
10

Looping continued
1.package main
2. …
3.
4.func main() {
5. i := 1
6. for i <= 10 {
7. fmt.Println(i)
8. i++
Output
1
2
3
4
5
6
7
8
9
10

If and else
1.package main
2. …
3.
4.func main() {
5. i := 22
6. if i > 10 {
7. fmt.Println(“big”)
8. } else {
Output
big

Struct
1.package main
2. …
3.
4.type PersegiPanjang struct {
5. P, L int
6.}
7.func main() {
Output
{10 22}

Array, slice, map, methods, pointer,
interfaces etc.
https://tour.golang.org/list

People will tend to say ...
concurrency is doing two or more things
simultaneously,
parallelism is doing two or more things
simultaneously.

concurrency is not parallelism

concurrency
“Gue lagi ngobrol
sambil ngopi”
parallelism
“Gue lagi ngoding
sambil denger musik”

concurrency is the composition of
independently executing processes

parallelism is the simultaneous
execution of (possibly related)
computations

concurrency is about dealing with lots
of things at once. parallelism is about
doing lots of things at once

concurrency is about the structure.
while parallelism is about the
execution.

but, concurrency can enable parallelism

to have true parallelism you need to
run your program on a machine with
multiple physical processors

Imagine you have a restaurant
you have no employee
You only have one stove
there is one customer
she orders “omelette” and “french fries”

Without concurrency
1.you go to the kitchen
2.you make omelette
3.when omelette is done, give it to the customer
4.you go back to the kitchen
5.you make french fries
6.when french fries is done, give it to the
customer

With concurrency
2.you ask your employee to cook french fries
3.you make omelette OR your employee make french
fries
4.when omelette/french fries is done, give it to
the customer
NOTE: THIS TIME YOU HAVE ONE
EMPLOYEE BUT YOU ONLY HAVE ONE
STOVE

With concurrency + parallelism
2.you ask your employee to cook french fries
3.you make omelette AND your employee make
french fries
4.when omelette/french fries is done, give it to
the customer
NOTE: THIS TIME YOU HAVE ONE
EMPLOYEE AND YOU HAVE TWO
STOVES

1 2 3 4 5 6 7 8 9 10
DOCTOR
IN (4 MINUTES)
CHECK-UP (5 MINUTES)
TIME REQUIRED FOR 1 PERSON
4 + 5 = 9 MINUTES
TIME REQUIRED FOR ALL PERSON
9 * 10 = 90 MINUTES
WITHOUT
CONCURRENCY

1 2 3 4 5 6 7 8 9 10
DOCTOR
IN (4 MINUTES)
TIME REQUIRED FOR 5 PERSON
4 + 5 * 5 = 29 MINUTES
29 * 2 = 58 MINUTES
WITH
CONCURRENCY

1 2 3 4 5 6 7 8 9 10
DOCTOR
4 + 5 * 5 = 29 MINUTES
WITH
CONCURRENCY +
PARALLELISM
DOCTOR

Companies currently using Go throughout the world
https://github.com/golang/go/wiki/GoUsers

Where to go
Tour of Go (https://tour.golang.org)
Go by Example (https://gobyexample.com/)
An Introduction to Programming in Go (https://www.golang-
book.com/books/intro)
Google it.

Golang 101 (Concurrency vs Parallelism)

More Related Content

Similar to Golang 101 (Concurrency vs Parallelism)

Recently uploaded

Golang 101 (Concurrency vs Parallelism)

Editor's Notes