Search for the Memory Duplicities in the Java Applications Using Shallow and Deep Object Comparison

In high-level object languages, such as Java, a problem of unnecessary duplicates of instances can easily appear. Although there can be a valid reason for maintaining several clones of the same data in the memory, often it indicates that the application can be refactored into a more efficient one. Unnecessary instances consume memory, but in case of Java applications can also have a significant impact on the application performance, as they might prolong the time needed for the garbage collection. In this paper, we are presenting a method and a tool that allows detecting duplicity in the heap dump of a Java application, based on the shallow and deep object comparison. The tool allows to identify the problematic instances in the memory and thus helps programmers to create a better application. On several case studies, we also demonstrate that the duplicates appear not only in the student projects and similar programs that often suffer from poor maintenance but also in commonly available Java tools and frameworks.