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NodeJs
This document discusses Node.js and its event loop model. It explains that Node.js uses a single-threaded event loop model that handles concurrent connections through non-blocking I/O and event callbacks. It also discusses how the cluster module allows Node.js applications to take advantage of multi-core systems by load balancing workers across CPU cores.
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NodeJs
- 1. Architecture Load balancerClusterEvent loop Introduction
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- 4. Event loop execution stack contextswitching
- 5. Event loop varhttp = require('http'); http.createServer(function(req, res) { res.writeHead(200, { 'Content-Type': 'text/plain' }); res.end('Hello'); }).listen(8888); wrk2 -R 50000 -d 15s -t 4 -c 20 http://localhost:8888/ Running 15s test @ http://localhost:8888/ 4 threads and 20 connections Thread calibration: mean lat.: 3809.653ms, rate sampling interval: 13459ms Thread calibration: mean lat.: 3809.566ms, rate sampling interval: 13467ms Thread calibration: mean lat.: 3808.688ms, rate sampling interval: 13459ms Thread calibration: mean lat.: 3810.143ms, rate sampling interval: 13459ms Thread Stats Avg Stdev Max +/- Stdev Latency 8.90s 953.41ms 10.75s 60.16% Req/Sec nan nan 0.00 0.00% 212176 requests in 15.00s, 30.15MB read Requests/sec: 14145.13 Transfer/sec: 2.01MB 2013 MacBook Pro Retina with a 2.4 GHz Intel Core i5 and 8 GB 1600 MHz DDR3
- 6. Event loop HTTP pipelining HTTP/1.1assumes every connection is persistent — i.e. both ends should keep the TCP connection open — until one of the parties sends a Connection: close header. But even though the connection is kept open, the client should still wait for the server response before sending in another request.
- 7. Architecture V8 thread poolevent loop libuv node bindings node standard library node execution stack event loop socket readable http parse load(index.html) javascript C
- 8. Load balancer wrk-d 30s -t 12 -c 5000 12997 mysite 20 0 657m 39m 5556 R 109 1.0 0:22.44 12998 mysite 20 0 656m 38m 5556 S 55 1.0 0:09.85 12995 mysite 20 0 656m 37m 5564 R 53 1.0 0:09.84 12994 mysite 20 0 656m 38m 5556 R 51 1.0 0:09.40 The numbers 109, 55, 53 and 51 represent the CPU usage here 1018 mysite 20 0 659m 58m 5576 R 68 1.5 0:04.60 1023 mysite 20 0 659m 58m 5576 R 68 1.5 0:05.00 1024 mysite 20 0 659m 58m 5576 S 62 1.5 0:05.00 1030 mysite 20 0 659m 58m 5576 S 56 1.5 0:04.28 NGINX NODE 15050 mysite 20 0 658m 55m 5572 S 38 1.4 1:31.88 15063 mysite 20 0 659m 56m 5568 S 38 1.4 1:33.23 15058 mysite 20 0 657m 55m 5568 R 37 1.4 1:30.06 15071 mysite 20 0 658m 55m 5568 S 37 1.4 1:30.41 NODEHAPROXY
- 9. Cluster When using thecluster module in your application, your application is free to spin up as many workers as necessary to accommodate the load your application will receive. Though generally it is suggested to match the number of workers to the number of threads or logical cores your environment has available to it. The logic that encompasses your master process can be as simple or as complex as you want it to be, at the very least it will need to be able to spin up your workers when needed. It is ideal to make sure your master is keeping track if workers exit and if it's necessary to create new workers. The logic that makes up a worker is dependent on your application, but any socket opened in a worker will be shared among all workers in the pool. The design is such that you can write your logic once and spin up as many workers without having to worry about the synchronization of sockets on your own A downside of this single-threaded approach is that Node.js doesn't allow vertical scaling by increasing the number of CPU cores of the machine it is running on without using an additional module, such as cluster const cluster = require('cluster'); const http = require('http'); const numCPUs = require('os').cpus().length; if (cluster.isMaster) { // Fork workers. for (var i = 0; i < numCPUs; i++) { cluster.fork(); } cluster.on('exit', function(worker, code, signal) { console.log(‘worker ${worker.process.pid} died’); }); } else { // Workers can share any TCP connection // In this case it is an HTTP server http.createServer(function(req, res) { res.writeHead(200); res.end('hello worldn'); }).listen(8000); }
- 10. Node.js Application Area Node.jscan be used to create following types of applications. 1. E-Commerce Web Applications 2. Social Media Applications 3. Proxy Server 4. Real-time Services 5. Real-time data Applications like Multiplayer Games, Stock Trading, Chat App etc. 6. Data Streaming Applications 7. Network Applications 8. High Concurrency Applications 9. File Uploading Tools 10. Process Monitoring Tools 11. HTTP Web Server Who use Node.js 1. Walmart 2. E-bay 3. PayPal 4. Microsoft 5. LinkedIn 6. Yahoo 7. Google 8. SAP 9. IBM 10. Strong Loop 11. Dropbox
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