longjohn

longjohn

Long stack traces for node.js with configurable call trace length

Inspiration

I wrote this while trying to add long-stack-traces to my server and realizing that there were issues with support of EventEmitter::removeListener. The node HTTP Server will begin to leak callbacks and any of your own code that relies on removing listeners would not work as anticipated.

So what to do... I stole the code and rewrote it. I've added support for removeListener along with the ability to cut off the number of async calls the library will trace. I hope you like it!

Please thank tlrobinson for the initial implementation!

Production Use

Longjohn collects a large amount of data in order to provide useful stack traces. While it is very helpful in development and testing environments, it is not recommended to use longjohn in production. The data collection puts a lot of strain on V8's garbage collector and can greatly slow down heavily-loaded applications.

Installation

Just npm install it!

$ npm install longjohn

Usage

To use longjohn, require it in your code (probably in some initialization code). That's all!

if (process.env.NODE_ENV !== 'production'){
  require('longjohn');
}

// ... your code

Options

Limit traced async calls

longjohn.async_trace_limit = 5;   // defaults to 10
longjohn.async_trace_limit = -1;  // unlimited

Change callback frame text

longjohn.empty_frame = 'ASYNC CALLBACK';  // defaults to '---------------------------------------------'

Use with Source Maps

As of version 0.2.9 longjonn supports source maps. Just compile your code down to javascript with source map support and run like normal.

For coffee-script, this would look like:

$ coffee --map --compile script.coffee