To view the list of new instances, click the number in the Diff column. When there are new instances, their number will appear in parentheses in the Diff column. The Memory tab will now store the information on the instances of the selected class created after this moment. Right-click a class and select Track new instances. In addition to getting the number of instances, you can record which particular instances were created and where in the call stack that happened. When viewing instances of a class, right-click an instance and click Calculate Retained Size. Prior to running the application, make sure that the Attach memory agent option is enabled in Settings | Build, Execution, Deployment | Debugger. Also, this can be useful when making a decision on which data structure to use (for example, ArrayList vs. This can be useful when estimating the memory footprint of heavy singletons or data read from disk, for example, a complex JSON. Retained size is the amount of memory that the object itself occupies together with all the objects it refers to and that are not referenced by other objects.

You can explore the contents of each object and filter the list using a condition.įor example, to get the list of all empty String objects, double-click String on the Memory tab and enter this.isEmpty() in the Condition field.įor each class instance, you can calculate its retained size. The Diff column shows if the number of instances has changed.Ī dialog opens that lists all live instances of the selected class. Resume the program execution or step through the code.Ĭollect instances data at the second point. For this, you can collect the information twice and compare it using the built-in Diff feature.Ĭollect instances data at the starting point. Sometimes it is useful to know how many objects have been created since some point. Get the diff between two execution points The name filter will be applied dynamically as you type. Clicking the already selected criterion changes the order (ascending/descending). To sort the classes, click the corresponding header ( Class, Count, or Diff). The number of corresponding live objects is shown in the Count column.

The list of all loaded classes appears on the Memory tab. In the Memory tab, click Load classes (for performance, the Memory tab only collects the data on demand). Stop at a breakpoint or manually suspend the program. Get the information on the number of objects The Memory tab shows the following information:Ĭount: the number of class instances (objects) in the heapĭiff: the difference in the number of instances between two execution points

Hide/show Memory tabĬlick in the top-right corner of the Debug tool window, then click Memory. In such cases, combining the Memory tab with the Show Referring Objects option lets you easily find the leak.Īlso, examining the memory usage helps you better understand what is going on under the hood and optimize the program by minimizing the creation of unnecessary objects. For example, inner classes may prevent the outer classes from becoming eligible for garbage collection, which may eventually result in an OutOfMemoryError. Code examination alone might not provide any clues as some errors are easy to overlook. This information is useful for detecting memory leaks and their causes. IntelliJ IDEA lets you track the instances and analyze the conditions that cause objects to spawn or be retained. But in applications where you don’t know how much data you might be processing, it’s important that your recursive algorithms are tail-recursive, otherwise you’ll get a nasty StackOverflowError.When debugging, you can use the Memory tab to view details of all objects in the heap. I use this simple, basic form of recursion when I know that I’m working with limited data sets. For functions without deep levels of recursion, there’s nothing wrong with the algorithms shown in the previous lessons.

Java visualizer and stacks