Performance:
*
Event Loop
Event Loop
suggest changeBlocking Operation Example
let loop = (i, max) => {
while (i < max) i++
return i
}
// This operation will block Node.js
// Because, it's CPU-bound
// You should be careful about this kind of code
loop(0, 1e+12)Non-Blocking IO Operation Example
let i = 0
const step = max => {
while (i < max) i++
console.log('i = %d', i)
}
const tick = max => process.nextTick(step, max)
// this will postpone tick run step's while-loop to event loop cycles
// any other IO-bound operation (like filesystem reading) can take place
// in parallel
tick(1e+6)
tick(1e+7)
console.log('this will output before all of tick operations. i = %d', i)
console.log('because tick operations will be postponed')
tick(1e+8)
In simpler terms, Event Loop is a single-threaded queue mechanism which executes your CPU-bound code until end of its execution and IO-bound code in a non-blocking fashion.
However, Node.js under the carpet uses multi-threading for some of its operations through libuv Library.
Performance Considerations
- Non-blocking operations will not block the queue and will not effect the performance of the loop.
- However, CPU-bound operations will block the queue, so you should be careful not to do CPU-bound operations in your Node.js code.
Node.js non-blocks IO because it offloads the work to the operating system kernel, and when the IO operation supplies data (as an event), it will notify your code with your supplied callbacks.
Found a mistake? Have a question or improvement idea?
Let me know.
Table Of Contents
1
npm
8
Readline
12
Environment
15
Cluster mode
25
async.js
26
File upload
33
Debugging
41
cli
43
grunt
45
metalsmith
58
TCP Sockets
59
Hack
64
ES6
67
Redis
69
MongoDB
74
Sequelize.js
77
Oracle DB
81
Eventloop
83
passport.js
86
MongoDB
87
Lodash
88
CSV parsing
91
CORS
92
Profiling
93
Performance
95
OAuth 2.0
105
N-API
106
Multi-threading
108
Require
111
Contributors