Analyzing histories of code clones is important for understanding how they affect software development and developers. For this, many studies have been devoted to the approach of tracking code clones. However, to the best of our knowledge, no existing studies have attempted to track code clones in long-term and fine-grained change histories.In this paper, we report on the analysis of histories of method-level code clones hosted by a fine-grained version control system called historage, which allowed us to track source code entities across commits.We have tracked and analyzed method-level code clones in 10 open source software projects and found out that (1) in many projects, method-level code clones are removed regardless of whether they were changed or how frequently they were changed, and (2) a group of method-level code clones created at the same time tend to survive longer than those created individually. We believe that these findings will provide useful insights for future research on code clones such as determining the priority of code clone management.
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