  Code review is an important quality assurance activity for software
development. Code review discussions among developers and maintainers can be
heated and sometimes involve personal attacks and unnecessary disrespectful
comments, demonstrating, therefore, incivility. Although incivility in public
discussions has received increasing attention from researchers in different
domains, the knowledge about the characteristics, causes, and consequences of
uncivil communication is still very limited in the context of software
development, and more specifically, code review. To address this gap in the
literature, we leverage the mature social construct of incivility as a lens to
understand confrontational conflicts in open source code review discussions.
For that, we conducted a qualitative analysis on 1,545 emails from the Linux
Kernel Mailing List (LKML) that were associated with rejected changes. We found
that more than half 66.66% of the non-technical emails included uncivil
features. Particularly, frustration, name calling, and impatience are the most
frequent features in uncivil emails. We also found that there are civil
alternatives to address arguments, while uncivil comments can potentially be
made by any people when discussing any topic. Finally, we identified various
causes and consequences of such uncivil communication. Our work serves as the
first study about the phenomenon of in(civility) in open source software
development, paving the road for a new field of research about collaboration
and communication in the context of software engineering activities.
