Computer bugs: Born in the wee hours

Computer programmers create bugs more frequently in the wee hours of the morning than at other times — or so they say. They are the authors of a study presented this past weekend in Honolulu, at the 8th Working Conference on Mining Software Repositories:

Do time of day and developer experience affect commit bugginess?” by Jon Eyolfson, Lin Tan and Patrick Lam [pictured here] of the University of Waterloo. They report [the boldface emphasis is ours]:

“Modern software is often developed over many years with hundreds of thousands of commits…. In this paper, we study the correlation between a commit’s bugginess and the time of day of the commit [and other factors]….

“Our main findings include: (1) commits submitted between midnight and 4 AM (referred to as late-night commits) are significantly buggier and commits between 7 AM and noon are less buggy.”

Here is one of the informative graphs in the study:

BONUS: Investigator Mark Dionne writes: “Related: In the book Peopleware, about software engineering, the authors say:”

“A Cornell experiment in the 1960s polled a group of computer science students and divided them into those who liked to work with music in the background and those who didn’t. They put 1/2 of each group together in a silent room, and the other 1/2 in a different room equipped with headphones and a musical selection. To no one’s surprise, they performed about the same in speed and accuracy of completing a Fortran programming task. The part of the brain required for arithmetic and related logic is unbothered by music which is handled by another brain centre.

“There was a hidden wildcard. The specification required an output data stream be formed through a series of manipulations on numbers in the input data stream. Although unspecified, the net effect of all the operations was that each output number was equal to its input number. Of those students who figured this out, the overwhelming majority came from the quiet room. Not all work is centred around the same left part of the brain. There are occasional breakthroughs that may save months or years or work involving right-brain function.”