Mobile apps have become ubiquitous. For app developers, it is a key priority
to ensure their apps' correctness and reliability. However, many apps still
suffer from occasional to frequent crashes, weakening their competitive edge.
Large-scale, deep analyses of the characteristics of real-world app crashes can
provide useful insights to guide developers, or help improve testing and
analysis tools. However, such studies do not exist -- this paper fills this
gap. Over a four-month long effort, we have collected 16,245 unique exception
traces from 2,486 open-source Android apps, and observed that
framework-specific exceptions account for the majority of these crashes. We
then extensively investigated the 8,243 framework-specific exceptions (which
took six person-months): (1) identifying their characteristics (e.g.,
manifestation locations, common fault categories), (2) evaluating their
manifestation via state-of-the-art bug detection techniques, and (3) reviewing
their fixes. Besides the insights they provide, these findings motivate and
enable follow-up research on mobile apps, such as bug detection, fault
localization and patch generation. In addition, to demonstrate the utility of
our findings, we have optimized Stoat, a dynamic testing tool, and implemented
ExLocator, an exception localization tool, for Android apps. Stoat is able to
quickly uncover three previously-unknown, confirmed/fixed crashes in Gmail and
Google+; ExLocator is capable of precisely locating the root causes of
identified exceptions in real-world apps. Our substantial dataset is made
publicly available to share with and benefit the community.Comment: ICSE'18: the 40th International Conference on Software Engineerin