By Ido Sarig
Half way into the 2010-2011 NBA basketball season, the Pacific division leading LA Lakers had an embarrassing loss to the bottom-dwelling Memphis Grizzlies. The LA Times described the performance of several of the players at the Sunday, Jan.2, 2011 game as “sleep walking” – which turned out to be not far from the truth!
If this sounds familiar to iPhone users, it’s because it was a repeat of a nearly-identical episode, reported just two months earlier, when the iPhone alarm application failed to operate properly after the switch back from Daylight Saving Time to standard time.
What does this have to do with software engineering? It illustrates a well-known phenomenon in large-scale software applications, researched as early as the 1970s, when IBM performed a “distribution analysis of customer reported defects against their main commercial software applications” and were “surprised to find that defects were not randomly distributed through all of the modules of large applications” – or in plain English – some parts of the code are more buggy than others.