Flutter Memory Leak Detection Tool (HarmonyOS Adaptation)

Harmony OS Next

Leak Detector

Flutter Memory Leak Detection Tool (HarmonyOS Adaptation)

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Getting Started

Initialization

To avoid crashes in the underlying vm_service library, initialize before adding memory leak detection objects:

// maxRetainingPath: Maximum length of the reference chain (shorter values improve performance but may truncate leak paths; default is 300)
LeakDetector().init(maxRetainingPath: 300);

Note: Enabling leak detection may degrade performance due to full GC cycles. The plugin uses assert statements, so it does not need to be disabled in release builds.

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Detection

Add LeakNavigatorObserver to MaterialApp to automatically detect memory leaks in pages and their associated StatefulWidget states:

import 'package:leak_detector/leak_detector.dart';

@override
Widget build(BuildContext context) {
  return MaterialApp(
    navigatorObservers: [
      LeakNavigatorObserver(
        // Skip validation for specific routes (e.g., root '/')
        shouldCheck: (route) => route.settings.name != null && route.settings.name != '/',
      ),
    ],
  );
}

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Retrieve Leak Information

Register a listener for onLeakedStream to receive leak notifications with reference chain data:

LeakDetector().onLeakedStream.listen((LeakedInfo info) {
  // Print reference chain to console
  info.retainingPath.forEach((node) => print(node));

  // Show leak preview page
  showLeakedInfoPage(navigatorKey.currentContext!, info);
});

The LeakedInfo object includes:

• Class information for each node in the reference chain
• Referenced property details
• Source code declaration locations (file:line:column)

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Memory Leak History

Retrieve historical leak records:

getLeakedRecording().then((List<LeakedInfo> infoList) {
  showLeakedInfoListPage(navigatorKey.currentContext!, infoList);
});

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Troubleshooting Real-Device vm_service Connection Issues

Problem:
vm_service operates in ​Single Client Mode:

• When DDS (Dart Development Service) connects to vm_service, it enters single-client mode.
• Subsequent WebSocket connections (e.g., from leak_detector) are blocked until DDS disconnects.

Solutions:

1. Manual Reconnection:

• Disconnect from the computer after running flutter run.
• Restart the app (avoids DDS interference).

1. Disable DDS: Add --disable-dds to flutter run to bypass the debugger’s DDS service:

   flutter run --disable-dds

This ensures leak_detector can connect directly to vm_service on the device.