Group objects by class

One effective technique of Java memory profiling involves grouping objects by their classes to evaluate the resource usage and potential bottlenecks.

YourKit Java Profiler allows you to group objects by their classes, and evaluate how much memory they use. Upon accessing the view, you'll find presented the estimated retained sizes instead of precise measurements, as the latter might not be readily calculable. To obtain accurate measurements, click on the Calculate exact retained sizes tooltip located above the Retained Size column. Nonetheless, for the majority of classes, the estimated size closely approximates the exact value.

Why group objects by classes?

Instant visibility

When objects are grouped by their classes you instantly get a holistic view of the resource allocation. This aids in identifying which classes are consuming the most resources.

Easier analysis

When looking at a large heap dump, knowing the proportion of memory consumed by each class can help pinpoint potential areas for optimization.

Anomaly detection

Unusual amounts of instances for a particular class could indicate a design issue or a memory leak, thus serving as a red flag for deeper investigation.

Pinpointing memory leaks

Identifying suspects

Grouping by classes can also help identify potential memory leaks. If you notice a specific class continually increasing in instance count during your testing cycle without ever decreasing, that's a potential leak.

Path to GC roots

Use YourKit Java Profiler to analyze the path to the Garbage Collector (GC) roots for instances of suspicious classes. If there's no valid reason for the object to be retained, you've likely found a memory leak.