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![Running Node
~/ node
> var x=1, y=2, z=3;
> x+y+z
REPL
6
> require('fs').statSync('./blocking.js')
{ dev: 234881026,
Read-Eval-Print-Loop ino: 3162208,
mode: 33188,
nlink: 1,
.....
node app.js arg1 arg2
Invoke script process.argv[0]
process.argv[1]
===
===
"node"
"app.js"
process.argv[2] === "arg1"
process.argv[3] === "arg2"](https://image.slidesharecdn.com/nodejs-async-for-the-rest-of-us-110803083928-phpapp02/85/Node-js-async-for-the-rest-of-us-13-320.jpg)
![{
"name": "express",
package.json
"description": "Sinatra inspired web development framework",
"version": "3.0.0",
"author": "TJ Holowaychuk <tj@vision-media.ca>",
"contributors": [
{ "name": "TJ Holowaychuk", "email": "tj@vision-media.ca" },
{ "name": "Aaron Heckmann", "email": "aaron.heckmann+github@gmail.com" },
{ "name": "Ciaran Jessup", "email": "ciaranj@gmail.com" },
{ "name": "Guillermo Rauch", "email": "rauchg@gmail.com" }
],
"dependencies": {
"connect": ">= 1.5.2 < 2.0.0",
"mime": ">= 0.0.1",
"qs": ">= 0.3.0"
},
"devDependencies": {
"connect-form": "0.2.1",
"ejs": "0.4.2",
"expresso": "0.8.1",
"hamljs": "0.5.1",
"jade": "0.13.0",
"stylus": "0.13.0",
"should": "0.2.1",
"express-messages": "0.0.2",
"node-markdown": ">= 0.0.1",
"connect-redis": ">= 0.0.1"
},
"keywords": ["framework", "sinatra", "web", "rest", "restful"],
"repository": "git://github.com/visionmedia/express",
"main": "index",
"bin": { "express": "./bin/express" },
"scripts": {
"test": "make test",
"prepublish" : "npm prune"
},
"engines": { "node": ">= 0.4.9 < 0.7.0" }
}](https://image.slidesharecdn.com/nodejs-async-for-the-rest-of-us-110803083928-phpapp02/85/Node-js-async-for-the-rest-of-us-23-320.jpg)
![be weary of loops
for (var i=0, l=entries.length; i<l; i++) {
doSomething(entries[i]);
}
innocent enough?
if # entries = 10,000
doSomething() takes ~1ms
you block for 10 seconds!](https://image.slidesharecdn.com/nodejs-async-for-the-rest-of-us-110803083928-phpapp02/85/Node-js-async-for-the-rest-of-us-47-320.jpg)
![non-blocking loops
// order matters
function processEntry(entries, index) {
index = index || 0;
if(index === entries.length) return done();
doSomething(entries[index]);
process.nextTick(function() {
processEntry(entries, index++)
});
}
processEntry(entries);](https://image.slidesharecdn.com/nodejs-async-for-the-rest-of-us-110803083928-phpapp02/85/Node-js-async-for-the-rest-of-us-48-320.jpg)
![non-blocking loops
// order doesn't matter
var leftToProcess = entries.length;
for (var i=0, l=entries.length; i<l; i++) {
(function(foo) {
process.nextTick(function() {
doSomething(foo);
if(--leftToProcess === 0) {
done();
}
});
})(entries[i]);
}](https://image.slidesharecdn.com/nodejs-async-for-the-rest-of-us-110803083928-phpapp02/85/Node-js-async-for-the-rest-of-us-49-320.jpg)
![non-blocking loops
// order doesn't matter
// doSomething takes callback and is Async
// doSomethingAsync's happen in parallel
var leftToProcess = entries.length;
// doSomething's will be executed in parallel
for (var i=0, l=entries.length; i<l; i++) {
(function(foo) {
process.nextTick(function() {
doSomethingAsync(foo, function() {
if(--leftToProcess === 0) {
done();
}
});
});
})(entries[i]);
}](https://image.slidesharecdn.com/nodejs-async-for-the-rest-of-us-110803083928-phpapp02/85/Node-js-async-for-the-rest-of-us-50-320.jpg)
![Thank You!
Questions?
Mike Brevoort
@mbrevoort
mike [at] brevoort [dot] com](https://image.slidesharecdn.com/nodejs-async-for-the-rest-of-us-110803083928-phpapp02/85/Node-js-async-for-the-rest-of-us-57-320.jpg)
![Running Node
~/ node
> var x=1, y=2, z=3;
> x+y+z
REPL
6
> require('fs').statSync('./blocking.js')
{ dev: 234881026,
Read-Eval-Print-Loop ino: 3162208,
mode: 33188,
nlink: 1,
.....
node app.js arg1 arg2
Invoke script process.argv[0]
process.argv[1]
===
===
"node"
"app.js"
process.argv[2] === "arg1"
process.argv[3] === "arg2"](https://image.slidesharecdn.com/nodejs-async-for-the-rest-of-us-110803083928-phpapp02/75/Node-js-async-for-the-rest-of-us-13-2048.jpg)
![{
"name": "express",
package.json
"description": "Sinatra inspired web development framework",
"version": "3.0.0",
"author": "TJ Holowaychuk <tj@vision-media.ca>",
"contributors": [
{ "name": "TJ Holowaychuk", "email": "tj@vision-media.ca" },
{ "name": "Aaron Heckmann", "email": "aaron.heckmann+github@gmail.com" },
{ "name": "Ciaran Jessup", "email": "ciaranj@gmail.com" },
{ "name": "Guillermo Rauch", "email": "rauchg@gmail.com" }
],
"dependencies": {
"connect": ">= 1.5.2 < 2.0.0",
"mime": ">= 0.0.1",
"qs": ">= 0.3.0"
},
"devDependencies": {
"connect-form": "0.2.1",
"ejs": "0.4.2",
"expresso": "0.8.1",
"hamljs": "0.5.1",
"jade": "0.13.0",
"stylus": "0.13.0",
"should": "0.2.1",
"express-messages": "0.0.2",
"node-markdown": ">= 0.0.1",
"connect-redis": ">= 0.0.1"
},
"keywords": ["framework", "sinatra", "web", "rest", "restful"],
"repository": "git://github.com/visionmedia/express",
"main": "index",
"bin": { "express": "./bin/express" },
"scripts": {
"test": "make test",
"prepublish" : "npm prune"
},
"engines": { "node": ">= 0.4.9 < 0.7.0" }
}](https://image.slidesharecdn.com/nodejs-async-for-the-rest-of-us-110803083928-phpapp02/75/Node-js-async-for-the-rest-of-us-23-2048.jpg)
![be weary of loops
for (var i=0, l=entries.length; i<l; i++) {
doSomething(entries[i]);
}
innocent enough?
if # entries = 10,000
doSomething() takes ~1ms
you block for 10 seconds!](https://image.slidesharecdn.com/nodejs-async-for-the-rest-of-us-110803083928-phpapp02/75/Node-js-async-for-the-rest-of-us-47-2048.jpg)
![non-blocking loops
// order matters
function processEntry(entries, index) {
index = index || 0;
if(index === entries.length) return done();
doSomething(entries[index]);
process.nextTick(function() {
processEntry(entries, index++)
});
}
processEntry(entries);](https://image.slidesharecdn.com/nodejs-async-for-the-rest-of-us-110803083928-phpapp02/75/Node-js-async-for-the-rest-of-us-48-2048.jpg)
![non-blocking loops
// order doesn't matter
var leftToProcess = entries.length;
for (var i=0, l=entries.length; i<l; i++) {
(function(foo) {
process.nextTick(function() {
doSomething(foo);
if(--leftToProcess === 0) {
done();
}
});
})(entries[i]);
}](https://image.slidesharecdn.com/nodejs-async-for-the-rest-of-us-110803083928-phpapp02/75/Node-js-async-for-the-rest-of-us-49-2048.jpg)
![non-blocking loops
// order doesn't matter
// doSomething takes callback and is Async
// doSomethingAsync's happen in parallel
var leftToProcess = entries.length;
// doSomething's will be executed in parallel
for (var i=0, l=entries.length; i<l; i++) {
(function(foo) {
process.nextTick(function() {
doSomethingAsync(foo, function() {
if(--leftToProcess === 0) {
done();
}
});
});
})(entries[i]);
}](https://image.slidesharecdn.com/nodejs-async-for-the-rest-of-us-110803083928-phpapp02/75/Node-js-async-for-the-rest-of-us-50-2048.jpg)
![Thank You!
Questions?
Mike Brevoort
@mbrevoort
mike [at] brevoort [dot] com](https://image.slidesharecdn.com/nodejs-async-for-the-rest-of-us-110803083928-phpapp02/75/Node-js-async-for-the-rest-of-us-57-2048.jpg)
Uploaded byMike Brevoort
Node.js - async for the rest of us.
Node.js is an asynchronous JavaScript runtime that allows for efficient handling of I/O operations. The presentation discusses developing with Node.js by using modules from NPM, debugging with node-inspector, common pitfalls like blocking loops, and best practices like avoiding large heaps and offloading intensive tasks. Key Node.js modules demonstrated include Express for web frameworks and Socket.io for real-time applications.
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Node.js - async for the rest of us.
- 1. node.js asynchronous... for the rest of us Mike Brevoort 8.2.2011 DOSUG code sample can be found at https://github.com/mbrevoort/node.js-presentation
- 2. agenda the case fornode.js developing with node look at a few popular modules lessons from the trenches
- 4. typical n-tier run-a-round browser makes call to web server (waits) web server makes call to database (waits) web server returns result to browser Response time is dominated by time waiting
- 5. typical i/o latency L1: 3 cycles L2: 14 cycles RAM: 250 cycles DISK: 41,000,000 cycles NETWORK: 240,000,000 cycles L1 L2 RAM Disk Network 0 60,000,000 120,000,000 180,000,000 240,000,000 300,000,000 http://nodejs.org/jsconf.pdf
- 6. http://xach.livejournal.com/ 170311.html
- 7. “Most languages weredesigned to solve computational problems, but Node.js is different. Node.js was designed from the ground up to efficiently handle the communication that is at the heart of modern web applications.” http://www.joyentcloud.com/products/smart-appliances/ node-js-smartmachine/
- 8. node.js An Evented I/Onetwork server for Javascript created by sponsored by Ryan Dahl
- 9. Runs Javascript, butisn’t primarily Javascript http://platformjs.wordpress.com/2010/11/24/node-js-under- the-hood/
- 10. Why Javascript? most widelyused programing language of the web “never under estimate the power of familiarity and friendliness” - Stacey Higginbotham, GigaOM async by nature - the browser is a single threaded event loop BAH! It’s a toy language!
- 11. the event loop singlethreaded = no execution concurrency all execution initiated by an event events may have zero to many callbacks events are executed in order Tom Hughes-Croucher’s postman analogy
- 12. Installing node mac, linuxor windows (with cygwin hell) fear not! stable windows support coming in v0.6.0 (~3wks) # clone the git repo git clone git://github.com/joyent/node.git cd node # checkout the version you want git checkout v0.4.10 # build and install ./configure make && sudo make install
- 13. Running Node ~/ node > var x=1, y=2, z=3; > x+y+z REPL 6 > require('fs').statSync('./blocking.js') { dev: 234881026, Read-Eval-Print-Loop ino: 3162208, mode: 33188, nlink: 1, ..... node app.js arg1 arg2 Invoke script process.argv[0] process.argv[1] === === "node" "app.js" process.argv[2] === "arg1" process.argv[3] === "arg2"
- 14. Hello World HTTP Server var http = require('http'); http.createServer(function (req, res) { res.writeHead(200, {'Content-Type': 'text/plain'}); res.end('Hello Worldn'); }).listen(8080, "127.0.0.1"); console.log('Server running at http://127.0.0.1:8080/');
- 15. Not just HTTP varnet = require('net'); var server = net.createServer(function (socket) { socket.write("Echo serverrn"); socket.pipe(socket); }); server.listen(1337, "127.0.0.1"); http://nodejs.org/
- 16.
- 17. Developing with Node install node install npm your favorite text editor Sublime Text 2, Textmate, vim, Emacs, Eclipse, whatever
- 18. npm node package manager created by Isaac Schlueter (Joyent)
- 19. npm publish, install, discover, anddevelop node programs puts modules in a place where node can find them manages dependencies
- 20. npm search, install # install a module (copy to node_modules) npm install socket.io # install a specific version npm install socket.io@0.6.0 # install module globally npm install socket.io -g # search npm search socket #info npm info socket.io
- 21. npm registry http://registry.npmjs.org/
- 22.
- 23. { "name": "express", package.json "description": "Sinatra inspired web development framework", "version": "3.0.0", "author": "TJ Holowaychuk <tj@vision-media.ca>", "contributors": [ { "name": "TJ Holowaychuk", "email": "tj@vision-media.ca" }, { "name": "Aaron Heckmann", "email": "aaron.heckmann+github@gmail.com" }, { "name": "Ciaran Jessup", "email": "ciaranj@gmail.com" }, { "name": "Guillermo Rauch", "email": "rauchg@gmail.com" } ], "dependencies": { "connect": ">= 1.5.2 < 2.0.0", "mime": ">= 0.0.1", "qs": ">= 0.3.0" }, "devDependencies": { "connect-form": "0.2.1", "ejs": "0.4.2", "expresso": "0.8.1", "hamljs": "0.5.1", "jade": "0.13.0", "stylus": "0.13.0", "should": "0.2.1", "express-messages": "0.0.2", "node-markdown": ">= 0.0.1", "connect-redis": ">= 0.0.1" }, "keywords": ["framework", "sinatra", "web", "rest", "restful"], "repository": "git://github.com/visionmedia/express", "main": "index", "bin": { "express": "./bin/express" }, "scripts": { "test": "make test", "prepublish" : "npm prune" }, "engines": { "node": ">= 0.4.9 < 0.7.0" } }
- 24. npm install . package.jsonisn’t just for modules published to npm npm can help you manage and install dependencies in any project # from the same directory # as package.json npm install .
- 25. npm list ~/ npmlist my_project@0.1.0 /Users/mikebre/my_project !"# cluster@0.6.9 invalid $ %"" log@1.2.0 !"# connect-gzip@0.1.0 $ !"# connect@1.4.6 $ $ %"" qs@0.1.0 $ %"" mime@1.2.2 !"# date@1.0.1 $ %"" require-kiss@1.0.5 !"" docco@0.3.0 extraneous !"# express@2.3.2 $ !"" connect@1.4.6 $ !"" mime@1.2.2 $ %"" qs@0.1.0 !"" hbs@0.0.7 !"" log@1.1.0 extraneous !"" metrics@0.1.1 !"" request-forked@1.9.8 !"" semver@1.0.6 invalid %"# xml2js@0.1.6 %"" sax@0.1.4
- 26. a very strong community nodejs.org Google Group mailing list IRC #node.js on freenode Stack Overflow, LinkedIn groups nodeconf, node summercamp, etc.
- 27. debugging ndb - command linedebugger Eclipse debugger plugin for V8 node-inspector is very nice!
- 28. node-inspector uses WebKit Web Inspector # install with npm npm -g install node-inspector # start node-inspector node-inspector & # start node in debug mode node --debug app.js
- 29. profiling node-inspector optionally supports theV8 profiler collects CPU and heap snapshots Speaking of heaps...
- 30. garbage collection --trace-gcoption to watch GC behavior V8 is a VM --> must GC tuned for the browser 20Mb - 40Mb per tab Large node heap sizes == :(
- 31.
- 32. several popular node modules http://splashinthepacific.files.wordpress.com/2010/10/looking-glass-721.jpg
- 33. Express Sinatra (Ruby) inspiredweb framework created by TJ Holowaychuk
- 34. Express request routing content negotiation viewtemplating and partials session support static file serving fast, clean and powerful
- 35.
- 36. a RESTful service? cute,terse. boring let’s do something a bit more interesting...
- 37.
- 38. Socket.io Unified API forWebsockets + fallbacks created by Guillermo Rauch
- 39. Socket.io unified API forComet style apps transport negotiation server and client libraries feature rich, above and beyond what the websocket protocol prescribes heartbeats, timeouts, namespacing, volatile messages, message acknowledgements, etc.
- 40.
- 41.
- 42. asynchronous learning curve app.get('/bar', function(req, res) { foo.fetchSomething(function(error, something) { if(!error) { foo.fetchSomeOne(something, function(error, someone) { easy to if(!error) { foo.fetchBar(function(error, bar) { if(!error) { write } res.send("we got bar: " + bar); code else { res.send(error.statusCode); } like } }); this else { res.send(error.statusCode); } }); } else { res.send(error.statusCode); } }); });
- 43. uncaught errors on error, node emits an ‘error’ event on the corresponding object if no listeners on object for ‘error’, a top level exception is raised and the process exits > var server = http.createServer(function (req, res) {}); prudent server.on('error', function(error) { approach console.log("Caught error! Don't exit!"); }); nuclear approach > process.on('uncaughtException', function(error) { }); console.log("Kaboom.... handle " + error);
- 44. plan for multiple processesfrom the start each node process is bound to one core many small processes better than one big one use Cluster https://github.com/learnboost/cluster var cluster = require('cluster'); cluster('app.js') .set('workers', 16) // defaults to # of cores .use(cluster.logger('logs')) .use(cluster.stats()) .use(cluster.cli()) .use(cluster.repl(8888)) .listen('80')
- 45. keep the heapsmall 200Mb or less if you’re worried about GC pause move data out of the node process instead use Redis, MongoDb, etc encourages statelessness, encourages scalability reduces risk of losing a single node process
- 46. everything you do blocks No CPU for YOU! http://redriverpak.files.wordpress.com/ 2010/08/vwtouareg-road-block.jpg
- 47. be weary ofloops for (var i=0, l=entries.length; i<l; i++) { doSomething(entries[i]); } innocent enough? if # entries = 10,000 doSomething() takes ~1ms you block for 10 seconds!
- 48. non-blocking loops //order matters function processEntry(entries, index) { index = index || 0; if(index === entries.length) return done(); doSomething(entries[index]); process.nextTick(function() { processEntry(entries, index++) }); } processEntry(entries);
- 49. non-blocking loops //order doesn't matter var leftToProcess = entries.length; for (var i=0, l=entries.length; i<l; i++) { (function(foo) { process.nextTick(function() { doSomething(foo); if(--leftToProcess === 0) { done(); } }); })(entries[i]); }
- 50. non-blocking loops //order doesn't matter // doSomething takes callback and is Async // doSomethingAsync's happen in parallel var leftToProcess = entries.length; // doSomething's will be executed in parallel for (var i=0, l=entries.length; i<l; i++) { (function(foo) { process.nextTick(function() { doSomethingAsync(foo, function() { if(--leftToProcess === 0) { done(); } }); }); })(entries[i]); }
- 51. set ulimit -n nodecan handles 1000’s of connections? but your OS says... Too many open files default # file descriptors on most linux systems is 1024 1 FD per socket means max open sockets < 1024 increase the max # of file descriptors ulimit -n <max # FD> ulimit -a to see current max
- 52. pooled outbound connections node pools outbound http(s) connections by default for host + port combinations default concurrent maxSockets per host + port is 5 is this what you want? // for http as of node v0.4.10 require ('http') .getAgent("api.twitter.com", 80) .maxSockets = 100; // for https as of node v0.4.10 require ('https') .getAgent({ host:"docs.google.com", port: 443 }) .maxSockets = 100;
- 53. timeouts expect that anycallback could fail and may not be called anticipate conditions where both inbound or outbound connections may hang use Mikeal Roger’s ‘request’ module I contributed timeout functionality should be part of node core ~v0.7/0.8
- 54. offload anything computationally intensive spawn a child process require('child_process').spawn call out to another system more apt to handle heavy lifting use a job queue
- 55. be specific with packagedependencies { "name": "Foo Package", "description": "my Foo package", > "version": "1.0.0", "author": "Mike Brevoort <mikebre@ecollege.com>", "dependencies": { "express": "2.3.2", "cluster": ">= 0.6.1", is this what "mongodb": "0.9.x", "connect-gzip": "~0.1", you really "underscore": "= latest" want? really? }, "engines": { "node": "= 0.4.8" } }
- 56. Let me tellyou about my friend node he’s a great multi-tasker but can only do one thing at a time
- 57. Thank You! Questions? Mike Brevoort @mbrevoort mike [at] brevoort [dot] com
Editor's Notes
- #2 \n
- #3 Good Grief. Why do we need another...\n
- #4 the browser waits, the server waits - what&#x2019;s the difference?\n
- #5 \n
- #6 John McCarthy\n
- #7 \n
- #8 FAST, handles many connections\n
- #9 \n
- #10 \n
- #11 \n
- #12 \n
- #13 CommonJS Modules\nhttp library - node docs http://nodejs.org/docs/v0.4.10/api/\nnode will exit if it has nothing to do\n
- #14 \n
- #15 \n
- #16 \n
- #17 \n
- #18 \n
- #19 \n
- #20 \n
- #21 \n
- #22 \n
- #23 \n
- #24 \n