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Fault in Hong Kong Air Traffic system caused by exceeding 5500 user settings (scmp.com)
20 points by dklsf on April 16, 2017 | hide | past | favorite | 5 comments


This just doesn't add up to me.

5500 is an odd number (not power of two) which rules out some kind of overflow issue.

Was this some kind of fixed size database? Why would it have crashed when storing 5500 rows?

Maybe storing that many hit a timeout, and maybe they were stored outside a transaction, hence leaving the system in an inconsistent state? But that wouldn't explain the database shutting down.

Maybe they were trying to store 5500 but hit a limit at 4096 before getting there?

I feel something is lost in translation (between nerds and non nerds) in the explanation for this outage.


Yeah I had the same feeling; how could anyone writing something like an air traffic control system design it in such a way that some failure/exception in loading user settings causes the system to die?

This is probably a horrible mess of ancient java crap and the 5500 is just an arbitrary number that the store couldn't respond to in time before the app timed the con out; but having lived in mordor, a horrific data model which would enable this sort of thing to be a problem isn't too big of a stretch of the imagination.

My bigger question was what the hell kind of application needs 5k settings per user.....



This reminds me of junior (and sometimes not so junior) developers not protecting against the full range of possibilities in conditions, and how hard it's for some to understand that there's glitches that make the counter go +2 instead of +1 before arriving at the condition check.


Atrocious site. Popups before seeing site. Then difficult to scroll. Randomly navigates to a new story when scrolling.




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