Classifying field crash reports for fixing bugs: A case study of Mozilla Firefox

Many software systems support automatic collection of field crash-reports which record the stack traces and other runtime information when crashes occur. Analysis of field crash-reports can help developers to locate and fix bugs. However, the amount of crash-reports collected is often too large to handle. To reduce the amount of data for the analysis, the existing approaches group similar crash-reports together. A bug can trigger a crash in different usage scenarios. Therefore, the crash-reports triggered by the same bug may not be identical. Using the existing approaches, the crash-reports triggered by the same bugs can be distributed into different groups and one group may contain crash-reports triggered by different bugs. We perform an empirical study of crash-reports collected for Mozilla Firefox to analyze the impact of crash-report grouping and identify the characteristics of an efficient grouping. We observe that when a group contains crash-reports triggered by multiple bugs, it takes longer time to fix the bugs in comparison to the bugs where crash-reports triggered by each bug are grouped separately. To effectively reduce the bug fixing time, we propose a grouping approach, such that, each group contains the crash-reports triggered by only one bug. The case study shows that an effective grouping can reduce the bug fix time by more than 5%.