'Tis the season for finals, which means thousands of you are using Firecracker to study for your tests. This past weekend, we upgraded our database server to a new machine with 4x the hardware of the previous one. The new hardware gives us better redundancy against failure and much faster response times. In other words: Firecracker will respond faster and you will rarely see an error message.
How did we know this was necessary? We constantly monitor Firecracker to watch for bottlenecks and application throughput.
Every time you interact with our site (load a page, flag a topic, submit a recall score), we record how long it took our server to respond to your request. Over time, we can see how long the average response time is, to ensure we aren't getting slower over time as we add new features.
Real-time monitoring - We track in real-time how long each request takes in the various "layers" of our site: the database, application server, cache server, etc. Here's an example, which shows our average response time at just over 1/3 second:
Response Time Distribution - We monitor how long (in milliseconds) requests take to complete on Firecracker. The shorter, the better.
Requests Per Minute - To measure how high the demand is for our services, we keep track of Requests Per Minute. As you might expect, demand for Firecracker goes down at night, and then shoots back up during the day in the US. I've removed the Y-axis showing the exact numbers, but we use these data to schedule any downtime and release new features.
In addition to tracking Firecracker's overall performance, we monitor key parts of our app. We separately track response times in the Study Plan, Flagging Topics, Submitting Recall Scores, and Loading Quizzes.
For example, the first page you see upon signing into Firecracker is the Study Plan. This has everything from your flagged topics, to your calendar, to key performance metrics on it. We keep a close eye on how long it takes you to see something on the Study Plan page.
Good luck on your finals, and we promise to keep Firecracker fast and available for you!
- Tony Wieczorek, VP of Engineering @ Firecracker