EventLoop & libuv
Nairi
Harutyunyan
nairi.haroutiounian@gmail.com
@nairihar
#nodejsarmenia 🇦🇲
#nodeGS
Reactor Pattern
I/O request
Event Loop
Event
Demultiplexer
Event
Queue
Hardware
I/O
Enqueue Event
Execute Event Handler
> fs.readFile('./file.txt', cb);
>Â uv__fs_read(req)
> cb(null, data);
JavaScript Code
V8
Operating System
C++ Bindings
Core Modules
libuv
c-ares,
zlib,
etc...
Node.js architecture
require('main.node')
node-gyp
Macrotasks
setTimeout / setInterval
I/O
setImmediate
close events
process.exit
index.js
Event Loop
refs++
refs--
refs==0
refs=0
refs>0
EventLoop queues
Microtasks
setTimeout & setInterval
I/O
setImmediate
close events
process.exit
index.js
Event Loop
EventLoop queues
process.nextTick
Promise
Promise
nextTick
Timers
I/O
JavaScript queues
Timers
I/O
Immediate
close events
process.exit
Event Loop
index.js
queues
Promise
nextTick
queues
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
Â
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
NOW: Up to 1024 threads (after libuv v1.30.0 or node v12.5.0)