Tools of the Mad (Load Testing) Scientist - Creating Scary Load Test Profiles

As I  mentioned in my last post, I often stop by to see the mad load-testing Doctor at his very unassuming lab when I had some extra time, and when I had some extra homemade cookies with which to bribe him. It was amazing how the cookies could get him to tell me what secret projects he was currently working on. Singularly devoted to the concept of building the bullet-proof website, the Doctor was quite mad in his dream to never be caught in a situation for which his site or his infrastructure had not been fully tested.

Today was no different.

“Aha!” he said, “HERE is something you have never seen!  Some load test products just blast a site immediately, hitting the site with every one of the full amount of virtual users they are planning to use during the test, right from the beginning.  It seems like the testers are just trying to knock the site over.  This tells them virtually nothing. Then, there are other types of load tests that ramp up the number of virtual users in a straight line until they reach the maximum number of users they are going to use.  At least this will tell you WHEN the site falls over.  But there is never any such thing as a straight line in traffic on a real website, right?  Why use it in a load test?”

“Besides, there is so much more that load testing can tell us than just when a site falls over, such as a server reacts when briefly pushed past its maximum number of users, whether the site can run at say, 120% of users for 10 or 20 minutes, and still recover without degradation or errors, or whether they can see what a pattern of traffic peaks at the top of every hour, will do to their infrastructure and response times.”

“SO!!  I have developed a SCARY way of DRAMATICALLY varying the number of virtual users I am running against a site.  Using complex algorithms, that unfortunately take me a few days to build and debug between each run, I can have load tests with WILD peaks and valleys! My creation of the these monstrous load test profile will drive websites MAD!”

“The apple doesn’t fall far from the tree,” I mused silently.

“Doctor, have you checked out that website I told you about last time,”  I opened my laptop and showed him the site.  “In LoadUIWeb Pro, SmartBear has already created something they call the ‘Custom Shape Load Profile’.  Look, it is one of those features in the  ‘Ten Reasons to Go Pro’ they highlight in their documentation.”  I clicked a load test to edit, and showed him the Load Profile window:


“Doctor, here I can do those same steady load and stepwise load methods you mentioned at the beginning, but in addition, with a few clicks I can do a custom shape as well…”  I quickly drew one out with my touchpad:


“Never mind having to use complex math and algorithms, I can draw this out with my mouse, and run it immediately.  All it takes is a few clicks, and I am ready to go.”  I even went back and redrew another, more scary load test.


“Is this dramatic enough a load test for you to run?” I asked him.

His ice-blue eyes went wide.  “That is even scarier than MY creation!”  But you must have to do some math to make it run for a longer-duration load test…”

I clicked to the “Continuous Load” tab in the same window.

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