Last week I was sat with Simon, one of my client’s managers, as he showed me around their new customer support centre web app highlighting slow-loading pages. Simon, along with a couple of others, has been playing guinea pig using the new support centre in his day to day work.
The main rollout is in a few weeks but the performance problems have to be fixed first so support team members don’t spend a lot more time on calls, forcing customers to wait longer on hold before speaking to someone. Potentially bad for costs, customer satisfaction, and team morale!
Simon gave me a list of about a dozen trouble spots and I remoted into their production box to profile them all. I had to collect the results and get off as quickly as possible to avoid too much disruption; I could analyse them later on my own laptop. This gave me plenty of time to hunt down problems and suggest fixes.
I used Red Gate’s ANTS Performance Profiler throughout. One of the many helpful features it includes is bookmarking. You can mark any arbitrary time period in your performance session, give it a meaningful name (absolutely invaluable!), and use that as a shortcut to come back to it later.
For example, here I’ve selected the “Smart search” bookmark I created whilst profiling the support centre:
The call tree shows me the call stacks that executed during the bookmarked time period. Towards the bottom you can see that SQL queries are using the vast majority of time in this particular stack trace:
(Identifying SQL as a problem I took these queries and analysed them in more detail using both their execution plans, and SQL Server’s own SQL Profiler. I then suggested more efficient queries that could be used by NHibernate via repository methods.)
Also note we’re looking at Wall-clock time as opposed to CPU time. I won’t talk about the differences in detail here. What you need to understand is that Wall-clock time represents actual elapsed time. This matters because the queries execute in SQL Server, outside the IIS worker process running the site. Under CPU time measurements, which only include time spent in-process, they therefore wouldn’t appear as significant contributors to overall execution time.
Back on point: bookmarking is great as far as it goes, but you have to click and drag on the timeline after the fact to create them yourself. In the midst of an involved profiling session this is a hassle and can be error prone: what if by mistake you don’t drag out the full region you need to analyse? All too easily done, and as a result you can miss something important in your subsequent analysis.
Step in Live Bookmarks.
Basically, whilst profiling, you hit a button to start the bookmark, do whatever you need to do in your app, then hit a button to save the bookmark. Then you repeat this process as many times as you need. No worries about missing anything.
Here’s how it goes in detail:
- Start up a profiling session in ANTS Performance Profiler.
- Whilst profiling, click Start Bookmark. (To the right of the timeline.)
- Perform some action in your app – in my case I was clicking links to navigate problem pages, populate data, etc.
- Click Stop Bookmark.
- The bookmark is added to the list on the right hand side of the timeline. It’s generally a good idea to give your bookmark a meaningful name. To do this just click the pencil icon next on the bookmark and type in the new name.
- Rinse and repeat as many times as you need.
- When you’ve finished, click Stop in the top-left corner of the timeline to stop profiling.
It’s a good idea to save your results for later using File > Save Profiler Results, just in case the worst happens, and of course you can analyse them offline whenever you have time.
And that’s it: nice and easy, and very helpful when it comes to in depth performance analysis across a broad range of functionality within your application.
Any questions/comments, please do post below, or feel free to get in touch with me directly.