It was an alarming week. I am adjusting to my new job and one of the first tasks I was given was to build a push notification system for our API. The use case is parsing out vehicle recalls from a third party database and notifying users who have those vehicles about the recall and give them some details. However we also want to send notifications to old users who haven't logged in for a while, or users who use the app but don't have an account.
About halfway through building this feature I realized the scary part: Over the year this app has been live there are almost 25,000 users who meet some form of these three conditions.
The thing about working with PLCs and machines is that they really don't care what you ask them to do they typically will go along happily with your idea. 25,000 users very much do care, don't want to be bothered and will very unhappily let you know if there is a problem. As I kept working on this feature I grew more and more concerned. I attempted to re-assure myself: the worst case at your old job was destroying equipment or hurting someone...the worst case here is that users get the wrong notification or too many notifications or no notifications. It is way less risky. To no avail.
Push notifications were set to go off on Saturday morning. I had double & triple checked all my work, had a full suite of tests to back it up, it had been reviewed by a colleague and fully QA'd by our QA department and I STILL did not sleep Friday night and had to go exercise for 2 hours to try and keep my mind off of it.
In the end everything went well aside from one edge case that a couple dozen people were affected by (and has since been patched). Even now it seems funny to me that I was so stressed out about it - as someone who stresses very little and never had the same concerns working in much more dangerous conditions with more serious consequences..