Adam Wiggins, one of creator of Heroky wrote interested post about logging,
you may find it interesting
http://adam.heroku.com/past/2011/4/1/logs_are_streams_not_files/
On Monday, 28 April 2014 14:48:46 UTC+4, Jose Luis Rivas wrote:
>
> I would suggest you to not write directly but redirect output to a file.
>
> node app.js > file.log
>
> keep it simple.
>
> On 4/28/14, 5:45 AM, gen chen wrote:
> > I am now working on a node.js project based on cluster. I got stuck on
> > the logging. After doing some research, I worked out a solution. here
> > is it. i don't know if it is a good idea. The idea is like this. only
> > master process can wirte to the log file, if the current process is a
> > worker, then it send a log message to the master and then write to the
> > log file while the master can directly write to the log file. this can
> > avoid multiple process open and write to a same file.
> >
> > var util = require('util');
> > var fs = require('fs');
> > var cluster = require('cluster');
> >
> > var logger = module.exports;
> >
> > var levels = ['debug', 'info', 'warn', 'error', 'fatal'];
> > var logLevel = 'debug';
> >
> > var logfile = null;
> > var errorLogfile = null;
> >
> >
> > if(cluster.isMaster){
> >
> > logfile = fs.createWriteStream('debug.log', {flags:'a'});
> > errorLogfile = fs.createWriteStream('error.log', {flags:'a'});
> >
> > cluster.on('online', function(worker){
> > //collect log message from child and write to logfile.
> > worker.on('message', function(msg){
> > if(msg.type == 'logging') {
> > var level = msg.data.level;
> > var logStr = msg.data.msg;
> > if(levels.indexOf(level) >= levels.indexOf('error')){
> > errorLogfile.write(logStr + '\n');
> > }else{
> > logfile.write(logStr + '\n');
> > }
> > }
> > });
> > });
> > }
> >
> >
> > function log(level, args){
> >
> > if(levels.indexOf(level) < levels.indexOf(logLevel)) return;
> >
> > var args = Array.prototype.slice.call(args);
> >
> > args = args.map(function(a){
> > if(typeof a !== 'string')
> > return JSON.stringify(a);
> > else return a;
> > });
> > var msg = util.format.apply(null, args);
> >
> > var out = [];
> > out.push(new Date());
> > out.push('[' + level.toUpperCase() + ']');
> > out.push(msg);
> >
> >
> > if(cluster.isMaster){
> >
> > //write directly to the log file
> > if(levels.indexOf(level) >= levels.indexOf('error')){
> > errorLogfile.write(out.join(' ') + '\n');
> > }else{
> > logfile.write(out.join(' ') + '\n');
> > }
> >
> > }else{
> >
> > //send to master
> > cluster.worker.process.send({
> > type : 'logging',
> > data : {
> > level : level,
> > msg : out.join(' ')
> > }
> > });
> > }
> >
> > }
> >
> >
> > logger.debug = function(){log('debug', arguments);}
> > logger.info = function(){log('info', arguments);}
> > logger.warn = function(){log('warn', arguments);}
> > logger.error = function(){log('error', arguments);}
> > logger.fatal = function(){log('fatal', arguments);}
> >
> >
> >
> > --
> > --
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> --
> Jose Luis Rivas - http://joseluisrivas.net
> Venezuela - GPG: 0xB9AC8C43
>
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