Automatic categorization and visualization of lock behavior

Abstract

We consider the problem of understanding locking behavior in large Java programs using a combination of data collection, data analysis, and visualization. Our technique starts by collecting partial information about all locks used in the program. It then analyzes this information to determine sets of locks with common behaviors and to determine, for each set of locks, how that lock is used, e.g. if it is used as a mutex, semaphore, read-write lock, etc. The result of the analysis is then presented to the user who can select specific locks for full analysis during a subsequent run. Visualizing locking information is particularly difficult since the time scale of a lock can be ten or more orders of magnitude different from the time scale of the overall run and locks can be used millions of times. We provide different visualizations and visualization techniques for this purpose. First, we analyze either the partial or full traces and identify patterns of how each lock is used and display just those patterns along with their frequency. Second, we provide a thread-centric view of locking that supports fish-eye views at the microsecond level as well as time compression. Third, we provide a lock-centric view that is based on the specific type of lock to show its particular behavior.