Contents
Overview
I used to be annoyed by memory leak (and CPU load) when I use node.js for web app development.I tried to take snapshots and found bottle necks.
This article is how to take snapshot with memory and CPU.
We can check the result of snapshot with Google Chrome browser’s developer tool.
Work Environment
- OS
- Linux www4322gi 3.2.0-64-generic #97-Ubuntu SMP Wed Jun 4 22:04:21 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
- Node
- version: v0.10.26
- Library
Preparation
Install nvm and node.js here.Bulding
Make template with express
$ vim package.json
{
"name": "snapshot_test",
"version": "0.0.1",
"dependencies": {
"express": "4.8.7",
"ejs": "1.0.0",
"express-generator": "4.8.0"
}
}
$ npm install
$ ls node_modules/.bin/
express
$ ./node_modules/.bin/express -e -t ejs snapshot_test
$ ls snapshot_test/
app.js bin package.json public routes views
Development sample app
$ cd snapshot_test
$ vim package.json
{
"name": "snapshot_test",
"version": "0.0.0",
"private": true,
"scripts": {
"start": "node ./bin/www"
},
"dependencies": {
"express": "~4.8.6",
"body-parser": "~1.6.6",
"cookie-parser": "~1.3.2",
"morgan": "~1.2.3",
"serve-favicon": "~2.0.1",
"debug": "~1.0.4",
"ejs": "~0.8.5",
"request": "2.40.0",
"cheerio": "0.17.0"
}
}
$ npm update
routes/index.js
var express = require('express');
var router = express.Router();
var request = require('request');
var cheerio = require('cheerio');
/* GET home page. */
router.get('/', function(req, res) {
var url = 'http://160.16.71.152:12080/';
request(url, function (error, response, body) {
// Connection success
if (!error && response.statusCode == 200) {
// Parse
var $ = cheerio.load(body);
var hrefs = [];
// Retrieve all link urls in the page
$('a').each(function() {
hrefs.push($(this).attr('href'));
});
// return response
var result = {}
result.status = 'success';
result.contents = hrefs;
res.send(JSON.stringify(result));
// Error result
} else {
var result = {}
result.status = 'error';
result.contents = '';
res.send(JSON.stringify(result));
}
})
});
module.exports = router;
Development snapshot part
$ vim package.json
{
"name": "snapshot_test",
"version": "0.0.0",
"private": true,
"scripts": {
"start": "node ./bin/www"
},
"dependencies": {
"express": "~4.8.6",
"body-parser": "~1.6.6",
"cookie-parser": "~1.3.2",
"morgan": "~1.2.3",
"serve-favicon": "~2.0.1",
"debug": "~1.0.4",
"ejs": "~0.8.5",
"request": "2.40.0",
"cheerio": "0.17.0",
"nodegrind": "0.1.8",
"heapdump": "0.2.10"
}
}
$ npm update
routes/snapcpu.js
var express = require('express');
var router = express.Router();
var fs = require('fs');
var profiler = require('nodegrind');
router.get('/', function(req, res) {
// filename
var name = (new Date().getTime()) + '.cpuprofile';
// Start to measure
profiler.startCPU(name);
// Stop to measure after 5 sec
setTimeout(function(){
var cpuProfile = profiler.stopCPU(name, 'cpuprofile');
//Write profile
fs.writeFile(name, cpuProfile, function(err){
if (err) res.send(err);
else res.send('OK:' + name);
});
}, 5000);
});
module.exports = router;
routes/snapheap.js
var express = require('express');
var router = express.Router();
var fs = require('fs');
var heapdump = require('heapdump');
router.get('/', function(req, res) {
// filename
var name = (new Date().getTime()) + '.heapsnapshot';
// Take a snapshot of heap
heapdump.writeSnapshot(name, function() {
res.send('OK:' + name);
});
});
module.exports = router;
Routing Setting
app.js
var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
var routes = require('./routes/index');
var users = require('./routes/users');
var snapcpu = require('./routes/snapcpu');
var snapheap = require('./routes/snapheap');
var app = express();
// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'ejs');
// uncomment after placing your favicon in /public
//app.use(favicon(__dirname + '/public/favicon.ico'));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));
app.use('/', routes);
app.use('/users', users);
app.use('/snapcpu', snapcpu);
app.use('/snapheap', snapheap);
// catch 404 and forward to error handler
app.use(function(req, res, next) {
var err = new Error('Not Found');
err.status = 404;
next(err);
});
// error handlers
// development error handler
// will print stacktrace
if (app.get('env') === 'development') {
app.use(function(err, req, res, next) {
res.status(err.status || 500);
res.render('error', {
message: err.message,
error: err
});
});
}
// production error handler
// no stacktraces leaked to user
app.use(function(err, req, res, next) {
res.status(err.status || 500);
res.render('error', {
message: err.message,
error: {}
});
});
module.exports = app;
Behavior Check
$ curl http://127.0.0.1:3000
{"status":"success","contents":["http://160.16.71.152:12080/","http://160.16.71.152:12080/?page_id=382",.....................,"http://www.adazing.com/"]}
Check result of snapshot
Take snapshot of heap
$ for i in `seq 5`; do curl 'http://127.0.0.1:3000/'; sleep 1s; done $ curl http://127.0.0.1:3000/snapheap OK:1409475822884.heapsnapshot $ ls 1409475822884.heapsnapshot app.js bin node_modules package.json public routes views
Take snapshot of CPU
$ for i in `seq 10`; do curl 'http://127.0.0.1:3000'; sleep 1s; done # Do following command during for loop $ curl http://127.0.0.1:3000/snapcpu $ ls 1409475822884.heapsnapshot 1409477190566.cpuprofile app.js bin node_modules package.json public routes views
Result Check
