Measuring Performance with Boomerang
performance
tutorials
Boomerang by the Exceptional Performance team at Yahoo! is a way of measuring site performance from a visitor’s point of view. It can measure roundtrip time, bandwidth and latency.
Roundtrip measurements are the total time it takes to initiate a resource request to the point at which it is completely available. This is implemented by using event handlers on window.onunload and window.onload. The unload handler takes the time in milliseconds and stores it in a cookie, with the URL of the page. The onload event then compares the current time to the one in the cookie, or attempts to use the Web Timing API.
Timers can be associated with the entire page load time, or each resource within it.
Measuring Bandwidth and Latency
Use git to download the code into a suitable location on your web server:
cd /var/www/my_site/
git clone http://github.com/yahoo/boomerang.git
Then create a test HTML page like this one: gist: 458518.
The important piece of code here is this:
BOOMR.init({
user_ip: '10.0.0.1'
});
On a production site, the base_url would probably be a full path to where you keep boomerang — perhaps you have a separate server for static files. The authors recommend setting the IP address using server-side scripts.
The BOOMR.subscribe('before_beacon', ...) code is used instead of a remote beacon to print bandwidth and latency statistics. It’ll take a few seconds to display the stats after loading the page.
Other Use Cases
The Boomerang documentation has a full set of use cases with code samples: Use cases for boomerang.
The API documentation is fairly easy to follow too.
