Demystifying Memory Leaks in Android

Memory leaks can silently sabotage the performance and stability of Android applications, posing a significant challenge for developers. Memory leaks can be a silent and persistent performance killer. In this talk we will explore the causes, symptoms, and consequences of memory leaks, shedding light on how they can gradually degrade the user experience and impact device performance.

Transcript

1. Demystifying Memory Leaks in Android Yves Kalume Android Developer & GDE @kalumeyves
2. Tech communities journey • Started since 2019 • GDSC Lead 2021 • GDG Co-organizer 2022 • GDE for Android April 2023 ❤ Social impact (Devscast, Soracert)
3. The Goal 🎯
4. Memory management Management applied to computer memory • allocate portions of memory to programs at their request • free it for reuse when no longer needed.
5. #include <stdlib.h> void performOperations() { int* data = malloc(sizeof(int)); // Some operations on 'data'//. free(data); // Memory is properly freed } int main() { performOperations(); return 0; }
6. Memory leak When allocated memory is not released once it has been used (and is no longer useful).
7. #include <stdlib.h> void performOperations() { int* data = malloc(sizeof(int)); // Some operations on 'data'//. // Memory is not freed } int main() { performOperations(); return 0; }
8. Memory on the JVM • We are not required to implement memory management logic • Garbage collector • Object of our program are stored in the Heap • If the heap is full, you’ll get an OutOfMemoryError.
9. Garbage collection Mechanism to Automatically reclaim memory that is no longer in use by the program.
11. How does memory leak happen on the JVM ?? 🧐
12. When expected short-lived object are attached to long-lived one 👀
14. class MyActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { ... val textView = findViewById<TextView>(R.id.myTextView) MySingleton.leakedView = textView } } object MySingleton { var leakedView: View? = null }
15. We should not keep a reference to an object that is not useful anymore.
16. class MyActivity : AppCompatActivity() { ... override fun onDestroy() { super.onDestroy() MySingleton.leakedView = null } } object MySingleton { var leakedView: View? = null }
17. Tools to detect memory leak • Memory Profiler (Android Studio) • LeakCanary • …
18. How does LeakCanary works ?? 🤔
19. Detect retained objects • Determine the circumstances in which an object must be collected E.g : Activity onDestroy is called • Wait few seconds (5)
20. class App : Application() { private val lifecycleCallbacks = object : Application.ActivityLifecycleCallbacks { ... override fun onActivityDestroyed(activity: Activity) { shouldBeCollected.add(WeakReference<Activity>(activity)) } } override fun onCreate() { super.onCreate() this.registerActivityLifecycleCallbacks(lifecycleCallbacks) } }
21. Heap dump a snapshot of your application's memory in a point in time. • What types of objects your app has allocated, and how many of each. • How much memory each object is using. • Where references to each object are being held in your code.
22. Debug.dumpHprofData("location")
23. Analyzing the heap • Parses the .hprof file • Locates retained objects in that heap dump. • Finds the path of references • Produce leak trace.
24. val heapDumpFile = File(filesDir, "heapdump-file.hprof") Debug.dumpHprofData(heapDumpFile.absolutePath) heapDumpFile.openHeapGraph().use { //parse the file }
25. 4. Categorizing leaks • Application Leaks • A Library Leak
26. One more thing…
27. Maybe your application is already leaking memory 🤷
28. Some advices • Pay attention while using reference of activity, fragments,etc • Don’t forget to cancel threads API or Coroutines if they reference a view (or any short live object) • Use structured concurrency • Avoid to pass “this” to an object which lives longer than “this” • Use performance monitoring tools • There are memory leaks that you won't solve, but don't hesitate to report them.
29. Thank you ! Yves Kalume Android Developer & GDE @kalumeyves