Performance profiling - assess the number of items read during the execution of a method

Question

Is there some way to track the number of items read during the execution of a method?

If you look at hostname/sitecore/admin/stats.aspx you see values such as "Average Items", "Max Items" and "Total Items" retrieved per rendering. I'm thinking that if Sitecore can capture that info for a rendering, it must be possible to do the same for an individual method (or hierarchy of methods)?

Answer 1

The class of interest here is Sitecore.Diagnostics.PerformanceCounters.DataCount (in Sitecore.Kernel.dll). You can simply use the following technique:

var initialItemsAccessed = Sitecore.Diagnostics.PerformanceCounters.DataCount.DataItemsAccessed.Value;
SomeMethod();//the method you want to assess
var totalItemsAccessed = Sitecore.Diagnostics.PerformanceCounters.DataCount.DataItemsAccessed.Value - initialItemsAccessed;

The DataCount class has various other static counter properties which you can query in the same way.

I found this out by looking first at /Sitecore/admin/ShowConfig.aspx to see what processors are used within the mvc.renderRendering pipeline. Two processors are of interest here:

<processor type="Sitecore.Mvc.Pipelines.Response.RenderRendering.StartStatisticRecording, Sitecore.Mvc"/>

and

<processor type="Sitecore.Mvc.Pipelines.Response.RenderRendering.RecordStatistic, Sitecore.Mvc"/>

Looking at these, I saw a call to DataCount.DataItemsAccessed.Value which is used to query total items accessed before and after rendering the rendering.