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War story: the hardest bug I ever debugged

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462 points jakevoytko | 2 comments | 24 Mar 25 14:37 UTC | HN request time: 0.479s | source
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BobbyTables2 ◴[27 Mar 25 03:27 UTC] No.43490119[source]▶
Interesting writeup, but 2 days to debug “the hardest bug ever”, while accurate, seems a bit overdone.

Though abs() returning negative numbers is hilarious.. “You had one job…”

To me, the hardest bugs are nearly irreproducible “Heisenbugs” that vanish when instrumentation is added.

I’m not just talking about concurrency issues either…

The kind of bug where a reproduction attempt takes a week, not parallelizable due to HW constraints, and logging instrumentation makes it go away or fail differently.

2 days is cute though.

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efortis ◴[27 Mar 25 05:12 UTC] No.43490557[source]▶
Same here, we had an IE8 bug that prevented the initial voice over of the screen reader (JAWS). No dev could reproduce it because we all had DevTools open.
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1. smrq ◴[27 Mar 25 13:37 UTC] No.43493509[source]▶
I can't remember the actual bug now, but one of my early career memories was hunting down an IE7 issue by using bookmarklets to alert() values. (Did IE7 even have dev tools?)
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2. camtarn ◴[27 Mar 25 15:25 UTC] No.43494621[source]▶
There was a downloadable developer toolbar for IE6 and IE7, and scripts could be debugged in the external Windows Script Debugger. The developer toolbar even told you which elements had the famous hasLayout attribute applied, which completely changed how it was rendered and interacted with other objects, which was invaluable.