JarCastingHermes PageSpeed
What's this?
Hermes PageSpeed is a library and application for performance measuring of website load time. It's distinguishing features are twofold: it is programmable using the Selenium framework and it conducts repeated experiments to determine statistically significant results.
There are many good performance measurement tools available online. Several popular sites include Google's PageSpeed Insights, Yahoo's YSlow, and WebPageTest. This application allows you to measure site performance if you need to perform some kind of action in order to get to the page you want to measure, such as providing a username and password for example. The application performs multiple iterations of the experiment so that summary statistics for each measurement are generated.
Building
Hermes PageSpeed uses the ChromeDriver framework to issue commands to the Chrome browser. You must have the Chrome browser installed on the your machine. The framework is built using Apache Maven. Use mvn package to build the application.
Use
You must have the chromedriver binary either in your PATH or set the system property webdriver.chrome.driver. You must also be running a Selenium Server instance.
Run java -jar target/page-racer-[latest version]-uber.jar without any arguments to see a list of command line options. The --url and --output options are mandatory. The former specifies an url for measuring page load times and the latter specifies a path and filename for the gzipped output results. The python script bin/graph.py can be used to process the output results and generate pretty graphs. Example graphs are shown at the bottom of the page.
The primary entry points into this library are the com.addthis.site.test.framework and the com.addthis.site.test.configuration packages. To write your own test procedures use the the class Main as a template. The primary class that orchestrates the tests is PerformanceTest. It uses the builder pattern to create new tests. You will be instantiating instances of the Navigator and Transformer interfaces. The provided classes SinglePageNavigator and IdentityTransformer can either be used directly or as templates for your own tests.
Use and Abuse of Statistics
This tool can be used to generate summary statitics about a site of interest. It cannot determine at what point a site is ready for browsing or user interaction. Only you can make that determination. The application measures the load time for page assets. You must determine which page asset(s) you can use as a signal to indicate that the page is ready. For example if you know that an asset will be loaded on the bottom of the page off the screen that it will not be productive to use that asset as an indicator of page readiness.
Known Issues
On some linux systems you may need to install gconf if it is not present on your system. This is a ChromeDriver issue. You may also see the log messages "[WARNING]: PAC support disabled because there is no system implementation" and "Only local connections are allowed." Those messages can be ignored.
License
Hermes PageSpeed is released under the Apache License Version 2.0. See Apache or the LICENSE for details.
Example Usage
These are 100 iterations of measuring the Space Jam homepage.
The startTime of page resources.
The responseEnd of page resources.
The elapsed time of resource loads as calculated by (responseEnd - startTime).
The legend for previous three graphs.
Measurements from the Navigation Timing API.
