  Collaborative activities among knowledge workers such as software developers
underlie the development of modern society, but the in-depth understanding of
their behavioral patterns in open online communities is very challenging. The
availability of large volumes of data in open-source software (OSS)
repositories (e.g. bug tracking data, emails, and comments) enables us to
investigate this issue in a quantitative way. In this paper, we conduct an
empirical analysis of online collaborative activities closely related to assure
software quality in two well-known OSS communities, namely Eclipse and Mozilla.
Our main findings include two aspects: (1) developers exhibit two diametrically
opposite behavioral patterns in spatial and temporal scale when they work under
two different states (i.e. normal and overload), and (2) the processing times
(including bug fixing times and bug tossing times) follow a stretched
exponential distribution instead of the common power law distribution. Our work
reveals regular patterns in human dynamics beyond online collaborative
activities among skilled developers who work under different task-driven load
conditions, and it could be an important supplementary to the current work on
human dynamics.
