good evening again this is the first time

I'm seeing this okay I'm holding it up

this is a gopher Singapore edition so

gopher Merlion and the title of my talk

if I speak it quickly

oops stay

nvm it doesn't want to

title of my talk if you speak it quickly

is Go for you? That's a pun there.

All of us have limited mental capacity

limited mind budget

budget some of us can keep more things

in our mind some of us can keep less

things in our mind but you know in all

cases it's limited so what do you mean

by mine budget if you know how to drive

a car it's instinctive

you still know you still need to know

where you're going so that consumes

energy and mine budget so the point I'm

trying to ask is what are your current

skills what you currently do today and

what you want to do tomorrow so for

example if I currently write stuff for

the web

typically web front-ends I know

JavaScript quite well by definition but

I want to write back-end stuff around

the right back-end servers I want to

write API service your look you know

because you can write back-end stuff in

JavaScript it's called no GS you still

need to know about the rules of writing

API servers you still need to learn

about that domain but you don't have to

learn a new language because learning

new stuff consumes mine budget and it's

difficult

before coming to go I used to write in

Java so I know Java quite well and I

want to write web front-ends well you

can write web front-ends in Java it's

not impossible but it's like using that

to pull out nails so the point I'm

trying to say

the final point I'm trying to make is

you need to have the right tools so what

is goal good for so hammer is good for

hammering in stuff that cow hammer is

not good for pulling out nails go is

good for writing cloud services back-end

service it's good for being well this is

debatable but those people who have

written in go think it's actually quite

simple to read and understand it's good

for having this thing funny thing called

implicit interface satisfaction which

I'll talk about in a while it's got

fantastic concurrency and my favorite

feature its Java done right it's

cross-platform

Sogo is somewhat familiar that's the

first line hello will in go if you

ignore the funny fmt in the capital case

it's not a class print line it just goes

way of denoting a public variable you

see it's pretty much the same across

many many different languages so goal is

somewhat familiar and therefore somewhat

easy to learn in fact go about design to

be easy to learn anybody who comes from

a Java environment or c-lite language

will find go somewhat familiar go is

definitely type safe I like to I like to

put up this example do you think this

come this program will run do you think

this program will compile really compile

it won't even compile let's try how many

of you have run your presentations

before I'm going to run the presentation

and let's read their messages go error

messages are not too bad actually

so what it's done is taken this HTML fed

it into a temporary file called compiled

0 dot go and the compiler complained

cannot use B type string in an integer

for assignment can you do in JavaScript

yes or no yes let's prove it and you put

down a microphone

so I is definitely okay thank you my

anything so I is definitely an integer

now I is a string

javascript is bad truffles I'm starting

a flame war here actually not true

javascript is a pretty good language now

in a godo so let's talk about go alright

this one is not so obvious how strongly

typesafe is go

why type safety at all but let's let's

look at this code and let's see whether

it will compile at all

I declare a type called mynum as an

integer and over here I declare a

variable I it's of type my num and I

assign it the value two over here I

assign a variable J of type int integer

of value three can I assign I and J in

Java cannot can in ogs definitely can

bingo

No let's see the error message some of

you already guessed answer's no let's

look at error message

cannot use type J cannot use J type

integer as type mine um so my num

even though was derived from an integer

is a separate typing goal so it is very

very very strongly typed and this is

very useful if you write big code if you

write code that is shared with loads of

programmers it's also very useful for

code you have written years ago this is

the equivalent of keeping everything in

its right place and the right place for

everything but there's always two sides

to a coin keeping everything in the

right place takes a lot of time a lot of

bookkeeping nodejs

allows you to throw things all the place

a teenager's bedroom nodejs is like a

teenager's bedroom go is like a

well-kept well-groomed house so strong

static typing allows you to catch most

errors at compile time and the runtime

is quite predictable in other words

after compiling and you deploy

production you can expect predictable

performance but the flip side of it is

if you are trying to throw a no-show to

get a short script a language like

nodejs Python or Ruby is much more

appropriate so guess the message is what

do you want to do what you already know

and what you want to do in the future so

decide whether you want to learn go let

me try to convince you that go is worth

learning so go has implicitly satisfied

interfaces those come in from Java know

about Java interfaces go tries to keep

keeping a house in order

static typing strong static typing more

pleasant so over here I declare an

interface type it's called one D fire

and it's got one

that in it called quantify and quantify

it takes nothing and returns an integer

so over here I declare another type my

SDR or my string it's derived from type

string and it also has a quantify method

now how do I know there is a method this

funny syntax which go created the way

you read this line means quantify is a

method of s of type my string which

returns an integer that's how you read

it so basically it's a matter of my

string it says print that means printer

screen quantifying s and was s its

length of s it returns the length of s

as the funny has a final value this is

just a side effect you just print out

the string now I declare another type

called

my int and it's derived from integer and

to quantify this integer I did tell me

whether it's positive negative or zero

that simple code for that so let's cut

to the chase

well this code were let's go to line by

line

that's just a print statement this line

is interesting

oh by the way go has this funny reversed

declaration syntax so a variable Q is of

type quantifier that's why it means it

is not quantifier is of type 2 it's the

other way around so variable Q is of

type quantifier so the quantifier has a

quantified method Q equals my int 3 now

that's another funny go Lang go language

syntax all he's saying is victory and

make it my it so I'm casting 3 to my end

think of it like a constructor in Java

so that's a constructor kind of thing

print queue 25 so 3 is a numeric it's

positive so should be 1 I guess so

Q equals my string ABC and the length of

ABC is 3 so we run this program the

first one should be 1 the second one

should be 3 let's check it out and sure

enough it is 1 in 3 now

let me edit my presentation and rerun it

anybody learn how to edit your

presentation and rerun it let's change

this to a minus four let's editing my

presentation this is written in go by

the week

real cool stuff and let's run it again

so now it shows up as minus one can

everybody at a backseater bottom rows

good now no surprise if I change it to

zero it should be zero let's run it and

it shows up as zero if I change this to

a four letter word maybe a five letter

word it just returns the length of the

string now I'm going to show you goes

see you routes anybody know see here

good what do you think will happen here

0x20 a see that's a hexadecimal number

what do you think what happened you

volunteers shout out your answer really

will one character well let's try it on

quantifying euro 0x20 AC is the Unicode

for Euro the Euro symbol and the Euro

symbol is a single character string and

it says 3 because the signal character

string is actually an integer and it's

of length 3 really confusing stuff but

here are the things they will trip you

up it's sea routes

alright why is this useful why are these

car interfaces useful now let's say I

have another type call exam paper and

exam paper you submitted it as Syrian

Dom I shouldn't use Microsoft should use

Google stuff anyway that's the URL for

my exam paper submission and let's say

exam paper is to create me quantify how

do you test this car stuff it's

difficult right it's gonna make a

service call go out to the Internet

grab the real exam paper and try to test

it and that's not very predictable the

internet connection may be down I may

have changed my exam my exam submission

but I can have fake exam paper to HTTP

does not matter dot see you in the doc

it never makes the internet call but

fake exam paper because it

satisfies quantify it works and it's

great for testing so this is how I use

interfaces all the time but this way of

defining interfaces is very very useful

because in Java or similar languages you

must say this class implements this and

you may find that the implements may be

implements ABCD efg until Zach a very

very long string of implements in go

there is no implements cuit it's

implicit implementation so long as it's

got a quantifier method it works the

most fantastic example of this is IO

reader and IO writer you can print line

to a database because it I all right I

will read ok so that is the second

reason why go is such a good language if

I'm losing any of you if you want us any

questions just shout out interrupt me

yes

so Java has if you have a functional

interface yeah Java it onwards has

function interfaces and the question is

if you use the functional interface of

Java you have this kind of capability

sort of right and how is it different

from the Java interface well I like to

think go start the refers Java copied it

but here that's actually a very good

question

go JavaScript and I'm sorry

leave go office JavaScript nodejs Java

Kotlin all the new modern languages if

you hear one of the authors of go speak

his name is Robert by interesting

speaker he says all these languages are

becoming more and more alike they're

getting more and more features Java is

getting functional features node.js is

trying to get classes so all these

languages are converging more or less

the same language perhaps it differs

slightly different syntax who is

different go is very very limited I'd

want to use this word but it is quite

relevant limited stupid basic language

it is designed so that anybody coming

from a C language can look at it and

solve kind of understand it it's

designed so that you can write code that

is efficient that compiles quickly and

when you look at here five years later

you can still understand it so goal is

designed somewhat like Python what

design Python was designed to be clear

and easily readable so many people have

actually come from Python to go

why because Python is really slow global

interpreter lock

I came to go not from Python but from

Ruby the rubies are fantastic language

it makes developers like me who write in

Ruby very happy it's a very very fun

language but but but yes group global

interpreter lock it's really slow but

that wasn't my issue it was fast enough

Ruby was fast enough for me but Ruby

code because it was so fun to write when

you look at it five years later what am

I trying to write here go tries to

circumvent that problem by anyway let's

go to goes the feature which I want to

talk about which is concurrency which is

something which for a person new to

programming finds it really hard and for

person who does JavaScript finds it

quite hard as well so over here I

declare a function let's call plus and

all it does for event however prints

the plus sign that's all it does after

one second it Blin prints another plus

forever and ever

here we have basically the same routine

but it brings out a period brings out a

dot okay

most of us when we start out writing

code we write code like this this this

one compiled so

let's run it like this this one compiled

it all it's got some real error message

about to execute select so I'm about to

execute select fatal all goroutines are

sleep deadlock which means there is

something in NGO called a goroutine and

his detected deadlock and its crash the

program and it's exited so okay let's

make the program work

let's fix me ok let's run + let's run

this program ok pluses are running but

my aim is to run + and go at the same

time concurrently so as a beginner

programmer I would do that of course

do you think that will never work

no why

a sequential execution plus is holding

on to the CPU I just want to let go

let's prove it yes plus is hogging the

CPU doesn't want to let go it doesn't

let go any time to run it all okay I am

the creator I'm the right of this

program now dot can run correct yeah

don't runs by one go and plus and dot to

run at the same time how do I do that

anybody we got go experts here come on

ah yes the goalkeeper do ah start a go

routine let's do that

I added three characters g/o and a space

and I've turned a regular routine into a

go routine in the routine that doesn't

block let's prove it hey it doesn't

block it works but hold on this part the

code is not executing this particle

which says about to execute select is

not executing how do I get that to

execute as well

oh you guys are learning fast

put another make dot a go routine so

let's do that

bang now there's something interesting

here this comes from printing lying go

concurrency this comes from about to

execute select and then the pluses and

dots what is actually happened here is

the program ran put that into the

background it's running independently in

the background put that in a background

that took a few hundred microseconds

fraction of a millisecond so in a

fraction of a millisecond or maybe a

millisecond later the print line

executed and I needed to put this select

here select here select is a statement

which actually tries to determine which

grow routine is ready to run but if I

remove that select if I remove the wait

forever what do you think will happen

the program would actually the program

would terminate

what happened to my goal routines if

main terminates the core routines

dominate let's prove that

so no more select it's commented out and

by the way the double slash if you've

not figured it out its comment

program exited no dots no plus so that's

another feature of go

it has garbage collected the goal

routines goal is a garbage collector

language with a very very very

performant garbage collector those

people coming from Java every now and

then when the garbage collector collects

garbage it stops the world the whole

system stops go garbage collector used

to be like that as well stop the world

for a few hundred milliseconds the

latest version or go stops the world for

a few hundred microseconds so it doesn't

really stop the world alright

those people who know JavaScript will

know no js' that's nothing new

no Jas has concurrency as well so let's

prove it I'll put it here

f12 to get console

so over here I've defined two JavaScript

functions function plus and function dot

and this is very JavaScript every 1000

milliseconds lakh to the console a plus

every 1000 milliseconds log to the

console a - no - a dot so when I run

that well pluses go on to pluses four

pluses five pluses go on and on

if I run dot if I can type

now you got plus and dot's so javascript

can do what go to us mind budget if you

know JavaScript do you want to learn go

okay was it the same sort of sort of the

same what I just did in my in my web

browser was I made use of a web worker

which will consume this is roughly

equivalent to one java thread which is

roughly equivalent to one operating

system-level thread so if my computer

has four cores it can run four threats

at the same time at the same time you

can have many many threads like an when

you run for them at the same time a go

routine is not blind the JavaScript web

worker know a goroutine well a million

go routines can share one thread

somebody actually did a demo a million

go routine share one thread so it's a

very simple very lightweight go routine

almost does nothing but still a million

go routines can say one thread and on a

fork or machine you get four million go

routines so the next point I'll make is

ah after Java II guess guess who the

coffee

guess who do you copy the coffee go the

ideas are very old the ideas are very

very old right goroutine is actually not

the correct word to use it's correct in

go by it came from paper called

concurrently concurrent sequential

processes it's called co-routines

spelled with a c' nobody paid attention

to co-routines except for the line for a

long long time

right then goal came out and say

co-routines are cool and I'm gonna brand

them goroutines and then everybody

started saying hmm Cortland once it as

well

Java wants it as well so all these

languages are becoming known as the same

language with different syntax they're

getting features before coming to go yes

Rudy as a Jordi no I programmed in Java

and I was looking for better Java so I

thought Scala is good

Scala is an extremely powerful language

don't get me wrong it can do everything

you can write dsls domain-specific

languages in Java it is so big that I

can't read my code after one week I can

be so undisciplined there I cannot read

my own code after one week that is color

anyway

how good is gos concurrency that's

that's another thing I want to highlight

about goal is course concurrency good go

is design the birthplace of goal was

actually Google we are at its birthplace

the organization not here but

organization and goal was invented the

story goes when you're trying to compile

a big C++ program that big C++ program

took about 40 minutes to compile they

compile the equivalent program in go and

it took less than a minute few seconds

but compiled time is one thing how

performin is it this is a whole web

browser in go now those people working

in no job no GSA say I can have Express

and I can write a similarly short web

browser in three lines or four lines or

two lines

let's besides the point the point is can

no GS perform on my really crappy laptop

11,000 requests per second with almost

no optimization well go optimization

compared with nginx same laptop running

a static website all it does is serve

hello well it came out with about the

same 10,000 requests per second 11,000

requests the second it's within the

arrow pens right what I'm trying to say

here is for beginner who knows nothing

about OS tuning who knows nothing about

concurrency you can write code that's

production-ready

as good as engineer

so goal is designed for heavy-duty

back-end service production-ready

back-end service a really good really

performant easy to read easy to extend

back-end service and my favorite feature

of all Java done right if you use pure

go in other words you don't link against

the C library you can link go against a

CLI breathe that's called C go if we

don't use Seco or use Windows specific

dll's or Mac specific libraries you can

all you need to do to cross compile the

Gnostic oh you go enable equals zero

turn off Seco specify an operating

system windows I've got clients that

insist on using Windows what they do no

near windows old windows 386 windows now

x64 go Buell hello well it generates an

exe file a windows 386 exe file let's

look at the complete list

Hayek's

Wow Android Darwyn what's dragonfly

don't know what dragonfly is FreeBSD

some funny always called illumos I don't

know about it

ah this is really really really

interesting javascript was a web

assembly yes cool can compile to the

JavaScript web assembly binaries and

these people are using it because they

want to play games on the web browser

and go a so performin they put a whole

game engine in the web assembly with

with physics and everything in there

nice target before go is just another

target it targets all these platforms my

platform happens be Linux AMD 64 so

let's go back another presentation

if you won a coat download the whole

presentation download its there soohyun

github lots of other presentations there

as well but this one is there and you

can run your presentation like I ran my

presentation thanks for listening thank

you questions comments flamewars yes

okay the question was usually

machine-learning folks used something

like Python and Python is a fantastic

language for machine learning because

Python was written by dude over in

Russell my pronouncing that name all

wrong

he's a mathematics professor so before

tensorflow came out you had numpy and

Python was an absolutely great language

in that area go is not it's not a

machine language optimized language is

the wrong tool to use go for machine

language but go is very very good for

data engineering before you can do

machine learning you need to get your

data in shape you need to clean your

data so go has data flow libraries which

can clean up massive amounts of data

really quickly but not the actual

machine learning itself any other

questions comments reactions you like go

is it worth learning yes okay my friend

here has a difficult question for me he

promised me a difficult question doesn't

matter repeat your question yes

[Music]

okay okay I guess I guess you can

summarize the question is summarized the

question is can you share pine can you

share memory effectively if you got

sixty instances of the same thing can

you share memory sort of kind of it will

eat up it will be 60 times the memory

okay

so let's answer actually is a very very

good question

let me attack let me attack the first

question first let me address the first

question first go binaries can get

pretty big pretty fast that hello world

was about one to two megabytes why is it

so big why is a hello world almost two

megabytes

yes when you write a Java class

HelloWorld in Java class and the class

file is a few hundred bytes a go

executable is a few megabytes almost two

megabytes but the Java file can run on

its own you need the JVM which is 50

megabytes or more the last time I

checked the entire JVM for go the entire

go runtime is embedded in the binary the

entire go runtime the handles go

routines the entire go runtime that does

all this smart implicit interfaces

entire go runtime that does strong

static types is embedded in that one or

two megabytes in the hello world so most

go binaries are self-contained most HTTP

is not self-contained but you can make

it self-contained and can make a pure

coding net HTTP or the net library

actually makes use of the operating

systems resolver library which means

it's a time I'm a clear link library and

many pure go operas don't like it so

they turn off see go and you can produce

a pure goal binary and that consumes

maybe about five megabytes to eight

megabytes the entire web browser

resolver stack so that's why gold

binaries can get big quite fast the

entire docker binary was written in go

and it's about fifty megabytes I think

right so really really huge projects

like docker kubernetes cube control cube

CTL they win roughly tens of megabytes

when you deploy a goal binary in a

docker container I don't use Alpine

because I guess I just used from scratch

in docker terms from scratch means start

with an empty container empty docker

container and in my go binary is five

megabytes my docker containers five

megabytes really tiny docker containers

so the mantra for goal is don't

communicate by sharing memory right

don't communicate by sharing memory

share memory by communicating so

everything in goal is independent and

unshared non share you communicate

across different processes using

channels any other comments questions

reactions if not I think Xiao Zhang yes

yes I've used a patch a benchmark to

test the let me repeat the question for

the audience the question was is go now

because that hello world was static

content static web browsers everybody

knows it's blazingly fast right any any

person can write a fast static web

browser the question was is go the right

tool for IO intensive dynamic content

and absolutely that's the purpose of

goal it's designed to have very very

fast io intensive stuff if if everything

is compute intensive like video encoding

go will not be very effective because

the compute or CPU resource hungry

process will grab the CPU but if it is

IO intensive go is the perfect fit much

much much better than no GS know GS

rocked the world because it multiplexed

a lot of i/o intensive process

on two one thread go multiplex the same

thing actually cause some copy no GS in

their sense but knock not one trip on

all available threads if you have a 64

core CPU 64 processes can be called the

task versus one process in no js' and

yet that yes ok take two days

I'll just because need ok

go good for writing back in service

. go is fantastic for writing back-end

service second question is cool

resource-hungry does go require a lot of

resources like Java for example in the

answer is no go is very very efficient

next to see in terms of efficiency if C

was the ghost and there is one it uses

100% go would use maybe of 110% maybe

hundred five percent so it is very very

resource efficient thank you

[Applause]