You Don't Know Node.js EventLoop
Nairi
Harutyunyan
nairi.haroutiounian@gmail.com
@nairihar
#jsconfam18
- Event Loop
- Deep Dive into Libuv
- Macrotasks
- Microtasks
- Threads
- Why use Promise libs
Content
Node.js is a JavaScript runtime built on
Chrome's V8 JavaScript engine.
Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient.
What is Node.js
Reactor Pattern
event-driven model
I/O request
Event Loop
Event
Demultiplexer
Event
Queue
Hardware
I/O
Enqueue Event
Execute Event Handler
> fs.readFile('./file.txt', cb);
> uv__fs_read(req)
> cb(null, data);
Your Code
V8
operating system
C++ Bindings
Core Modules
libuv
c-ares,
zlib,
etc...
Node.js architecture
Macrotasks
Timers
I/O
Immediate
close events
process.exit
index.js
Event Loop
refs++
refs--
refs==0
refs=0
refs>0
Microtasks
Timers
I/O
Immediate
close events
process.exit
index.js
Event Loop
process.nextTick
Promise
Promise
nextTick
Timers
I/O
Timers
I/O
Immediate
close events
process.exit
Event Loop
index.js
process.nextTick
Promise
Promise
nextTick
Timers
I/O
Immediate
close events
process.exit
Event Loop
index.js
timers
I/O Poll
pending I/O callbacks
idle handlers
prepare handlers
Check handlers
Close handlers
Run expired timers
Run completed I/O handlers
Wait for I/O to complete
Some checking after polling
Run close handlers
libuv
JavaScript
Finished I/O work or I/O Errors
setTimeout
setInterval
setImmediate
.on('close'... handlers
epoll
kqueue
event ports
Thread Pool
linux
BSD
SunOS
IOCP
Windows
Network I/O
File I/O
DNS
...
libuv
Non-Blocking I/O
Blocking I/O
Threads
UV_THREADPOOL_SIZE=8 (SIZE<=128)
Thread pool
Blocking I/O
CPU intensive
Why use custom
Promise libs
Why not native
Timers
I/O
Immediate
close events
process.exit
Event Loop
index.js
Native Promise
Bluebird
Promise queue
Immediate queue
event in queue
callback
Summary
Node.js
libuv
c-ares
zlib
OpenSSL
http-parser
V8
npm
gyp
gtest
Queue
Timers
I/O
Immediate
close events
libuv
macrotask
Node.js
process.nextTick
Promise
Promise
nextTick
microtask