In this lab, you will experiment with a Node application that gradually slows down as more and more requests are made to the process. Over time, this becomes unbearable and administrators are used to forcing a restart; that's not how you roll, though, right?
NOTE: Unlike other exercises, this exercise is open-ended; we don't provide extraneous clues. It's up to you to use any of the tools from the previous exercises to diagnose this issue. If this is your first lab, perhaps you might want to consider looking at the Node Profiling with V8 or CPU Sampling with
perfand Flame Graphs labs first.
Navigate to the nodey directory. If you haven't yet, you should make sure all required packages are installed by running npm install. Then, run the following command to start our simple Node application:
$ ./run.sh
The application comes with a self-sufficient benchmark that reproduces the issue at hand by issuing 2500 POST requests to the /position endpoint, which is supposed to track accurate position information for certain real-world objects reported to the application. Run the following command to start the benchmark:
$ ./run.sh bench
You will see individual operations reporting their elapsed time. The time begins to degrade, and can reach 2x or worse in only a few seconds (after making a few hundred requests).
From here, you're on your own: profile the application using whatever tools you see fit, until you manage to pinpoint the problem. If you have time, try fixing the problem and running the benchmark again to make sure the issue is really gone.