Why do some renderings appear twice in Stats.aspx admin page

Question

I'm using the Stats.aspx (http://hostname/sitecore/admin/stats.aspx) admin page to identify the slowest components in my solution.

For some components, I see two entries e.g.

+--------------------------------------------------------------------------------------------------------------+----------------+------------+-----------+------------+------------------+-------------+
|                                                  Rendering                                                   | Avg. time (ms) | Avg. items | Max. time | Max. items |    Total time    | Total items |
+--------------------------------------------------------------------------------------------------------------+----------------+------------+-----------+------------+------------------+-------------+
| Gallery (/sitecore/layout/Renderings/Feature/MySolution/Media/Gallery)                                       |       306.3429 |        159 |  915.2689 |        469 | 00:00:00.9190289 |         479 |
| Controller: MySolution.Feature.Media.Controllers.GalleryController,MySolution.Feature.Media. Action: Gallery |       305.3223 |       9386 |  913.6628 |      28061 | 00:00:00.9159670 |       28158 |
+--------------------------------------------------------------------------------------------------------------+----------------+------------+-----------+------------+------------------+-------------+

The first is the path to the Rendering definition item, whereas the second is the assembly namespace/class of the controller for that same component. Why does the stats page represent the same thing twice and which one represents the true values?

Answer 1

Based on my investigation, the statistics of the rendering is added during the execution of the <mvc.renderRendering> pipeline. The method RecordStatistic is called at the end.

So, for every rendering being rendered on the page, Sitecore is adding the statistics so duplicate should not be present.

However, what may happened is that if you have 2 renderings: 1 controller rendering and 1 normal rendering, it may be that on some items you are using the rendering directly while on other items it may be the controller rendering.