Restart Node.js application when uncaught exception occurs
How would I be able to restart my app when an exception occurs?
process.on('uncaughtException', function(err) {
// restart app here
});
You could run the process as a fork of another process, so you can fork it if it dies. You would use the native Cluster module for this:
var cluster = require('cluster');
if (cluster.isMaster) {
cluster.fork();
cluster.on('exit', function(worker, code, signal) {
cluster.fork();
});
}
if (cluster.isWorker) {
// put your code here
}
This code spawns one worker process, and if an error is thrown in the worker process, it will close, and the exit will respawn another worker process.
You have a couple of options..
- Restart the application using monitor like nodemon/forever
process.on('uncaughtException', function (err) {
console.log(err);
//Send some notification about the error
process.exit(1);
});
start your application using
nodemon ./server.js
forever server.js start
- Restart using the cluster
This method involves a cluster of process, where the master process restarts any child process if they killed
var cluster = require('cluster');
if (cluster.isMaster) {
var i = 0;
for (i; i< 4; i++){
cluster.fork();
}
//if the worker dies, restart it.
cluster.on('exit', function(worker){
console.log('Worker ' + worker.id + ' died..');
cluster.fork();
});
}
else{
var express = require('express');
var app = express();
.
.
app.use(app.router);
app.listen(8000);
process.on('uncaughtException', function(){
console.log(err);
//Send some notification about the error
process.exit(1);
}
}
The answers/resolutions are collected from stackoverflow, are licensed under cc by-sa 2.5 , cc by-sa 3.0 and cc by-sa 4.0 .
