Mobile Memory and Resource Management Questions

Covers memory management principles and resource handling for mobile applications across platforms. Candidates should understand platform specific models such as automatic reference counting on iOS and garbage collection on Android, common causes of memory leaks and retain cycles, and how reference ownership and weak versus strong references affect lifetime. Include techniques for releasing resources correctly in lifecycle methods and avoiding long lived references that hold activity or context objects. Expect knowledge of memory profiling and diagnostics including tools and workflows for locating leaks and high memory usage, strategies to prevent out of memory conditions, and trade offs such as requesting a larger heap. Also cover cross platform considerations for frameworks like React Native and Flutter and practical practices for identifying and fixing real memory issues in production, such as analyzing heap dumps, using allocation instrumentation, and applying targeted fixes and regression tests.

EasyTechnical

0 practiced

Given the Android Activity code below, identify why it can leak memory and describe at least two code fixes.

java

public class MainActivity extends Activity {
    private final Handler handler = new Handler();
    @Override protected void onCreate(Bundle b) {
        super.onCreate(b);
        handler.postDelayed(new Runnable() {
            @Override public void run() {
                doHeavyWork(); // implicitly references MainActivity
            }
        }, 60000);
    }
}

Explain the leak cause and show code-level corrections (for example static handler pattern, weak references, or removing callbacks).

EasyTechnical

0 practiced

What are common causes of retain cycles and memory leaks in Flutter apps? Discuss scenarios such as State objects capturing callbacks or Streams without cancelling, Timers not cancelled on dispose, holding BuildContext across async gaps, plugin native resources not disposed, and global singletons that keep widget-related references.

EasyBehavioral

0 practiced

Tell me about a time you tracked down a memory leak in a mobile application. Structure your answer using the STAR method: Situation, Task, Action, Result. Explain the diagnostic tools you used, how you identified the root cause, what code changes you implemented, and how you verified the fix and prevented regressions.

MediumTechnical

0 practiced

Refactor the Swift code below to avoid a retain cycle without leaking, and explain why your solution is safe.

class MyViewController: UIViewController {
    var loader: NetworkLoader?
    override func viewDidLoad() {
        super.viewDidLoad()
        loader?.load { data in
            self.updateUI(with: data)
        }
    }
    func updateUI(with data: Data) { /* update views */ }
}

Show at least two valid refactorings (capture list or alternate ownership) and explain lifetime implications.

EasyTechnical

0 practiced

Describe the garbage-collection behavior of modern Android runtimes (ART). Cover generational aspects (young vs old regions if applicable), typical GC triggers (allocation pressure, native memory), stop-the-world pauses and their impact on UI responsiveness, and how allocation patterns (many short-lived objects vs large long-lived objects) influence GC frequency and behavior. List practical signs an engineer should watch for that suggest GC-induced UI jank.

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