b75e3660f4
During an evaluation of multiple loggers, I saw a slow down when trying to
quickly log more than 100,000 messages to a file:
```javascript
counter = 150000;
while (counter) {
logger.info('Message[' + counter + ']');
counter -= 1;
}
```
My detailed test can be found here:
- https://gist.github.com/NicolasPelletier/4773843
The test demonstrate that writing 150,000 lines straight in a FileStream
takes about 22 seconds until the file content stabilizes. When calling
logger.debug() 150,000 times, the file stabilizes to its final content
after 229s ( almost 4 minutes ! ).
After investigation, it turns out that the problem is using an Array() to
accumulate the data. Pushing the data in the Array with Array.push() is
quick, but the code flushing the buffer uses Array.shift(), which forces
re-indexing of all 149,999 elements remaining in the Array. This is
exponentially slower as the buffer grows.
The solution is to use something else than an Array to accumulate the
messages. The fix was made using a package called Dequeue
( https://github.com/lleo/node-dequeue ). By replacing the Array with
a Dequeue object, it brought the logging of 150,000 messages back down to
31s. Seven times faster than the previous 229s.
There is a caveat that each log event is slightly longer due to the need
to create an object to put in the double-ended queue inside the Dequeue
object. According to a quick test, it takes about 4% more time per call
to logger.debug().
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|---|---|---|
| examples | ||
| lib | ||
| test | ||
| .gitignore | ||
| .npmignore | ||
| .travis.yml | ||
| package.json | ||
| README.md | ||
log4js-node 
This is a conversion of the log4js framework to work with node. I've mainly stripped out the browser-specific code and tidied up some of the javascript.
Out of the box it supports the following features:
- coloured console logging
- replacement of node's console.log functions (optional)
- file appender, with log rolling based on file size
- SMTP appender
- GELF appender
- hook.io appender
- multiprocess appender (useful when you've got worker processes)
- a logger for connect/express servers
- configurable log message layout/patterns
- different log levels for different log categories (make some parts of your app log as DEBUG, others only ERRORS, etc.)
NOTE: from log4js 0.5 onwards you'll need to explicitly enable replacement of node's console.log functions. Do this either by calling log4js.replaceConsole() or configuring with an object or json file like this:
{
appenders: [
{ type: "console" }
],
replaceConsole: true
}
installation
npm install log4js
usage
Minimalist version:
var log4js = require('log4js');
var logger = log4js.getLogger();
logger.debug("Some debug messages");
By default, log4js outputs to stdout with the coloured layout (thanks to masylum), so for the above you would see:
[2010-01-17 11:43:37.987] [DEBUG] [default] - Some debug messages
See example.js for a full example, but here's a snippet (also in fromreadme.js):
var log4js = require('log4js');
//console log is loaded by default, so you won't normally need to do this
//log4js.loadAppender('console');
log4js.loadAppender('file');
//log4js.addAppender(log4js.appenders.console());
log4js.addAppender(log4js.appenders.file('logs/cheese.log'), 'cheese');
var logger = log4js.getLogger('cheese');
logger.setLevel('ERROR');
logger.trace('Entering cheese testing');
logger.debug('Got cheese.');
logger.info('Cheese is Gouda.');
logger.warn('Cheese is quite smelly.');
logger.error('Cheese is too ripe!');
logger.fatal('Cheese was breeding ground for listeria.');
Output:
[2010-01-17 11:43:37.987] [ERROR] cheese - Cheese is too ripe!
[2010-01-17 11:43:37.990] [FATAL] cheese - Cheese was breeding ground for listeria.
The first 5 lines of the code above could also be written as:
var log4js = require('log4js');
log4js.configure({
appenders: [
{ type: 'console' },
{ type: 'file', filename: 'logs/cheese.log', category: 'cheese' }
]
});
configuration
You can configure the appenders and log levels manually (as above), or provide a
configuration file (log4js.configure('path/to/file.json')), or a configuration object. The
configuration file location may also be specified via the environment variable
LOG4JS_CONFIG (export LOG4JS_CONFIG=path/to/file.json).
An example file can be found in test/log4js.json. An example config file with log rolling is in test/with-log-rolling.json.
By default, the configuration file is checked for changes every 60 seconds, and if changed, reloaded. This allows changes to logging levels to occur without restarting the application.
To turn off configuration file change checking, configure with:
var log4js = require('log4js');
log4js.configure('my_log4js_configuration.json', {});
To specify a different period:
log4js.configure('file.json', { reloadSecs: 300 });
For FileAppender you can also pass the path to the log directory as an option where all your log files would be stored.
log4js.configure('my_log4js_configuration.json', { cwd: '/absolute/path/to/log/dir' });
If you have already defined an absolute path for one of the FileAppenders in the configuration file, you could add a "absolute": true to the particular FileAppender to override the cwd option passed. Here is an example configuration file:
#### my_log4js_configuration.json ####
{
"appenders": [
{
"type": "file",
"filename": "relative/path/to/log_file.log",
"maxLogSize": 20480,
"backups": 3,
"category": "relative-logger"
},
{
"type": "file",
"absolute": true,
"filename": "/absolute/path/to/log_file.log",
"maxLogSize": 20480,
"backups": 10,
"category": "absolute-logger"
}
]
}
Documentation for most of the core appenders can be found on the wiki, otherwise take a look at the tests and the examples.
Documentation
See the wiki. Improve the wiki, please.
Contributing
Contributions welcome, but take a look at the rules first.
License
The original log4js was distributed under the Apache 2.0 License, and so is this. I've tried to keep the original copyright and author credits in place, except in sections that I have rewritten extensively.