I have a production bug... it only happens on Saturdays ever our ops folks have no idea - this can be replicated on a test server that gets no traffic.
If we reject the theory that it could be someone's elaborate revenge, Saturday may be the first day of the week that may become workday or non-workday because of incorrect assumption about the first day of the week. If everywhere but one place in your software the day numeration is correct it would be a hard bug to spot.
Also, if it is in Java, I vaguely remember there being a lot of ways to express weekday, so a lot of ways to shoot off your foot (solely on Saturday)
For bonus points, this failure is in a cron job that sends out recently queued messages. It runs once every ten minutes - last weekend we had 12 failures: four were in a cluster on their own, one was in a run of two, and six were in a single continuous run.
Please note that this server is unused by our business so no messages ever get naturally queued. Every day we sync the live production server to this server at about 9 PM - assuming an employee was queuing up a message before the snapshot is taken there might be a number of unsent messages in the snapshot - those messages will all be sent by the first cron job after the sync.
It is a wonderfully awful problem that has me wanting to pull out my luscious locks.
Yup, luck is appreciated and I'm trying to get more eyes but unfortunately I'm a senior dev that has the second highest seniority at the company so I feel guilty dragging others into it.
Please tell me it doesn't still happen when you emulate a different day of the week. Or is that non-trivial to even do because of technical debt? Either way, RIP weekends.
I've always hated recursion. It's always seemed like a cutesy programming trick that's not reliable in all conditions.
You could blow the stack in an edge case that you didn't think of. So it should never be a standard pattern. It's only good if you need to rewrite something for optimization and recursion is appropriate. But in many cases recursion is slower.
"Look at what I can do in 5 lines of code!" is for programming contests, not for anything important.