Track the Heap With Memory View

With Jetbrains‘ recent plugin, ‘JVM Debugger Memory View’ you can go the extra mile while debugging your applications in IntelliJ IDEA and Android Studio. If you want to keep an eye on the heap, the plugin is a valid tool to use during your debug sessions!

Memory View
A search in the Memory View.

Memory View basically lists a ton of Objects that are placed on the heap at the time present. It gives you the possibility to get a better feel of the current situation (at a breakpoint) of your application, memory-wise. The tool has packed its features inside a new tab in the IDE. You can find it by default in a panel on the right side.

In the overview you can see how many Objects have been added, removed when stepping over code. If you would place a few breakpoints you can easily view how the just executed code has affected the heap.

It is also possible to track new Instances of a particular Object. To do so you will need to turn on this feature for every class name listed.

Achievement instances in Memory View.
Achievement instances in Memory View.

Opening the class instances dialog enables filtering. Apply a filter with an evaluated expression.

Filtering in Memory View.
Filtering in Memory View.

Once you have a desired overview of instances you can unfold instances, just like you already could in the variables section in the regular debug mode. This is great for inspection of the objects. Objects where exceptions were raised properly stand out as well.

Furthermore, there is a possibility to view the call stack of the instance. When an object is selected you can view this in the stack frame on the right.

Another nice feature is the ‘Referring Objects For Object X’ one. To open up this frame, right click on an object and click ‘Show Referring Objects…’. You will now get a thorough overview of every referrer of the selected Object.

If you’ve gotĀ IntelliJĀ IDEA 2016.1 or higher, you can simply install the plugin from the Jetbrains repository.

As a side note I’d like to warn Android Studio users. The IDE may freeze due to a bug still present at the time of writing. Also, getting large amounts of instances could cause problems due to memory restrictions in Android. It seems the development is still ongoing. If you’ve found a bug, you can always log it in their issue tracker.