A Grails template rendering profiler

A complex grails page if often a cascade of templates rendering, nested in each others.
Optimizing page views starts with profiling which template takes time and which template is called by which one.
We offer a capture mechanism of all calls and several rendering: call stack, template time summary, and a visual display of the call graph.

Installation
grails install-plugin profile-template

Configuration
By default, all template calls are captured if the plugin is installed in your application. It is possible to deactivate the capture at start in your grails-app/conf/Config.groovy with:
profile.template.disabled=false

Accessing the data

A controller allows to interact with the profiling data: start/stop capture, clear all events and make reports:

http://localhost:8080/your-app/profileTemplateReport

All template events captured can be displayed from several point of views.

Call Stack

A list of calls of template rendering, where the indentation shows the nesting levels

A summary by template name

Where total and intrinsic duration are displayed ("intrinsic" means it is the time taken by the template itself minus the children times)

A call graph

Which template is called by which one? How many times? What is the sum of intrinsic duration for each template. This information is shown via a graphe, thanks to cytoscape.

How does it work?

Well, it is rather simple:

• the plugin PluginTemplateGrailsPlugin.groovy file contains a doWithDynamicMethods closure. This closure captures start & stop template rendering through StopWatchEvents, store into a service ProfileTemplateService.
• This service simply store the events by requests. They are store in memory, not to create any domain class and interfere with the host application.

Of course, as any profiling, it is not clever to use the plugin into the production application, nor to let the profiling capture last for too long.

Have fun profiling and don't hesitate to ask any question