Skip to content

Most visited

Recently visited

navigation

View the Java Heap and Memory Allocations with Memory Profiler

The Memory Profiler is a component in the Android Profiler that helps you identify memory leaks and memory churn that can lead to stutter, freezes, and even app crashes. It shows a realtime graph of your app's memory use, lets you capture a heap dump, force garbage collections, and track memory allocations.

To open the Memory Profiler, follow these steps:

  1. Click View > Tool Windows > Android Profiler (you can also click Android Profiler in the toolbar).
  2. Select the device and app process you want to profile from the Android Profiler toolbar. If you've connected a device over USB but don't see it listed, ensure that you have enabled USB debugging.
  3. Click anywhere in the MEMORY timeline to open the Memory Profiler.

Why you should profile your app memory

Android provides a managed memory environment—when it determines that your app is no longer using some objects, the garbage collector releases the unused memory back to the heap. How Android goes about finding unused memory is constantly being improved, but at some point on all Android versions, the system must briefly pause your code. Most of the time, the pauses are imperceivable. However, if your app allocates memory faster than the system can collect it, your app might be delayed while the collector frees enough memory to satisfy your allocations. The delay could cause your app to skip frames and cause visible slowness.

Even if your app doesn't exhibit slowness, if it leaks memory, it can retain that memory even while it's in the background. This behavior can slow the rest of the system's memory performance by forcing unnecessary garbage collection events. Eventually, the system is forced to kill your app process to reclaim the memory. Then when the user returns to your app, it must restart completely.

To help prevent these problems, you should use the Memory Profiler to do the following:

For information about programming practices that can reduce your app's memory use, read Manage Your App's Memory.

Memory Profiler overview

When you first open the Memory Profiler, you'll see a detailed timeline of your app's memory use and access tools to force garbage collection, capture a heap dump, and record memory allocations.

Figure 1. The Memory Profiler

As indicated in figure 1, the default view for the Memory Profiler includes the following:

  1. A button to force a garbage collection event.
  2. A button to capture a heap dump.
  3. A button to record memory allocations.
  4. Buttons to zoom in/out of the timeline.
  5. A button to jump forward to the realtime memory data.
  6. The event timeline, which shows the activity states, user input events, and screen rotation events.
  7. The memory use timeline, which includes the following:
    • A stacked graph of how much memory is being used by each memory category, as indicated by the y-axis on the left and the color key at the top.
    • A dashed line indicates the number of allocated objects, as indicated by the y-axis on the right.
    • An icon for each garbage collection event.

However, not all profiling data is visible by default. If you see a message that says, "Advanced profiling is unavailable for the selected process," you need to enable advanced profiling to see the following:

Record memory allocations

While viewing the heap dump is useful to see a snapshot of how much memory is allocated, it doesn't show you how the memory was allocated. For that, you need to record memory allocations. Once you finish a recording session, you can see the following for the recorded duration:

Figure 2. A complete allocation recording, as indicated by the vertical boundaries on the timeline

To view your app's memory allocations, click Record memory allocations in the Memory Profiler toolbar. While it records, interact with your app for as long as necessary to induce memory thrashing or memory leaks. When you're done, click Stop recording (the same button).

The list of allocated objects appears below the timeline, grouped by class name and sorted by their heap count, as shown in figure 2.

To inspect the allocation record, follow these steps:

  1. Browse the list to find objects that have unusually large heap counts and that might be leaked. To help find known classes, click the Class Name column header to sort alphabetically. Then click a class name. The Instance View pane appears on the right, showing each instance of that class, as shown in figure 3.
  2. In the Instance View pane, click an instance. The Call Stack tab appears below, showing where that instance was allocated and in which thread.
  3. In the Call Stack tab, click on any line to jump to that code in the editor.

Figure 3. Details about each allocated object appears in the Instance View on the right

By default, the list is arranged by class name. At the top of the list, you can use the drop-down on the right to switch between the following arrangements:

Capture a heap dump

A heap dump shows which objects your app is using memory at the time you capture the heap dump. Especially after an extended user session, a heap dump can help identify memory leaks by showing you objects still in memory that you believe should no longer be needed. Once you capture a heap dump, you can view the following:

Figure 4.

To capture a heap dump, click Dump Java heap in the Memory Profiler toolbar. While dumping the heap, the amount of Java memory might increase temporarily. This is normal because the heap dump occurs in the same process as your app and requires some memory to collect the data.

The heap dump appears below the memory timeline, showing all class types in the heap, as shown in figure 4.

To inspect your heap, follow these steps:

  1. Browse the list to find objects that have unusually large heap counts and that might be leaked. To help find known classes, click the Class Name column header to sort alphabetically. Then click a class name. The Instance View pane appears on the right, showing each instance of that class, as shown in figure 5.
  2. In the Instance View pane, click an instance. The References tab appears below, showing every reference to that object.

    Or, click the arrow next to the instance name to view all its fields, and then click a field name to view all its references. And if you want to view the instance details for a field, right-click on the field and select Go to Instance.

  3. In the References tab, if you identify a reference that might be leaking memory, right-click on it and select Go to Instance. This selects the corresponding instance from the heap dump, showing you its own instance data.

By default, the heap dump does not show you the stack trace for each allocated object. To get the stack trace, you must begin recording memory allocations before you click Dump Java heap. If you do, you can then select an instance in the Instance View and see the Call Stack tab alongside the References tab, as shown in figure 5. However, it's likely that some objects were allocated before you began recording allocations, so the call stack is not available for those objects. Instances that include a call stack are indicated with a "stack" badge on the icon .

Figure 5. The duration required to capture a heap dump is indicated in the timeline

In the list of classes, you can see the following information:

At the top of the class list, you can use the left drop-down list to switch between the following heap dumps:

By default, the list of objects in the heap are arranged by class name. You can use the other drop-down to switch between the following arrangements:

By default, the list is sorted by the Retained Size column. You can click on any of the column headers to change how the list is sorted.

In the Instance View, each instance includes the following:

This site uses cookies to store your preferences for site-specific language and display options.

Hooray!

This class requires API level or higher

This doc is hidden because your selected API level for the documentation is . You can change the documentation API level with the selector above the left navigation.

For more information about specifying the API level your app requires, read Supporting Different Platform Versions.

Take a one-minute survey?
Help us improve Android tools and documentation.