იოსებ ძმანაშვილი node.js

NODE.JS INTROA Talk By Ioseb Dzmanashvili

@iosebi

Wednesday, December 25, 13

ABOUT ME

Software Architect at AzRy LLC

Assistant Professor at CST

Ph.D Student at Technical University of Georgia

V8 Contributor

Wednesday, December 25, 13

ABOUT NODE.JS

Released in 2009 by Ryan Dahl

Is built on V8 JavaScript Engine

Based on event-driven non-blocking I/O

Platform for fast and scalable network apps

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WHAT MAKES IT AWESOME?

Easy of use

Server side JavaScript

Active community

Repository of awesome modules

npm install [module name]

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SERIOUSLY? IS THAT ALL?

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WELL, NO

Built on V8 JavaScript engine

Node.js never blocks on I/O operations

You do not need to manage threads

No expensive context switching

No memory waste on execution stacks

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V8 ADVANTAGES

Fastest JavaScript runtime

No JIT, it compiles JavaScript into Assembler

Short(really short) garbage collector cycles

Great implementation of EcmaScript 5 and EcmaScript 6

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MAJOR BOTTLENECKS

I/O operations (Disk, RAM, Network)

Threaded concurrency

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I/O LATENCY

I/O CPU Cycles

L1-Cache 3

L2-Cache 14

RAM 250

Hard Disk 41.000.000

Network 240.000.000

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WHAT CONTRIBUTES TO LATENCY?

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TYPICAL CODE EXAMPLE

var query = "SELECT * FROM t";var result = db.query(query);

while(result.hasNext()) { print(result.next());}

db.free(result);

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NON BLOCKING EXAMPLE

var query = "SELECT * FROM t";

db.query(query, function(result) { while(result.hasNext()) { print(result.next()); }});

// do something here

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FILE I/O EXAMPLE

$file = fopen("file.txt", "r");

while(!feof($file)){ $line = fgets($file); // do something with line}

fclose($file);

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ASYNC I/O WITH FILES

function readFile(file) { var br = new BufferedReader(file, ...); br.on("error", function(error) { // handle error }).on("line", function(line) { // do something meaningful with line }).on("end", function() { // we are done }).read();}

readFile("/path/to/file");

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HOW NODE.JS SOLVES I/O PROBLEMS FOR ME?

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SINGLE THREADED

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EVENT LOOP

SingleThread

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FS I/Ofn3();

PROGRAM EXECUTION FLOW

Program never waits for I/O operations completion

I/O is handled asynchronously

fn0();

fn1();

fn2();

DB I/O

FS I/O

NETWORK I/O

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DISADVANTAGES?

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IT IS JAVASCRIPT

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QUESTIONS?

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THANK YOU

Wednesday, December 25, 13