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run multi-threaded node.js network applications using the nativecluster module

• Run network applications within multiple processes multiplexed by node.js
• Easy to use, configless
• Standalone, no external process managers required
• Respawn dead/failed workers
• Gracefull application shutdown viasigterm
• Hot-Reload/Hot-Restart viasighup
• Delayed restart of failed processes to avoid infinite restart loops

$ npm install cluster-magic --save$ yarn add cluster-magic

A working snippet is available in theexamples directory. Just runnode examples/startup.js

File: startup.js

Initializes the cluster application

const_cluster=require('cluster-magic');const_app=require('./application.js');// start the clustered app (8 workers)_cluster.init(_app,{numWorkers:8});

File: application.js

Your socket based application which should be multiplexed

constnet=require('net');functionstartup(){constserver=net.createServer((socket)=>{// connections never end});server.listen(8000);}module.exports={// init hookinit:startup};

To hot-restart (zero downtime) an application, just send aSIGHUP to the master process.This spawns new workers and disconnects all current workers from thecluster-proxy

Example

# send SIGHUP to process 12345kill -HUP 12345

• SIGHUP Restart workers
• SIGTERM Gracefull application shutdown
• SIGINT Gracefull application shutdown

cluster-magic comes with as simple delayed-restart policy which suppresses infinite restart loops.

• In case a process dies, an internal counter will be incremented.
• If a threshold of10 is reached the process restart is delayed bycounter*200ms to avoid infinite restart loops on internal application errors.Well..this is may not what you expect from a "clustered application" but such an error requires that amanual fix will take place by the operations team (_logger.alert event is triggerd whichSHOULD be observed)
• The counter is decremented by 1 once per minute.

To specify the number of workers you can easily pass the environment variableNUM_WORKERS to the nodejs process. Default is set tonum_cpus*2

cluster-magic is OpenSource and licensed under the Terms ofThe MIT License (X11) - your're welcome to contribute