从实时数据更改 activity 导致内存泄漏

Question

我的代码：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main_navigation);
    bottomNavigationView = findViewById(R.id.bottom_navigation);
    subscribeObservers();
}

private void subscribeObservers() {
    if (!sessionManager.getAuthedUser().hasActiveObservers()) {
        sessionManager.getAuthedUser().observe(this, new Observer<AuthResource<LoggedUser>>() {
            @Override
            public void onChanged(@Nullable AuthResource<LoggedUser> loggedUserAuthResource) {
                if (loggedUserAuthResource != null) {
                    switch (loggedUserAuthResource.status) {
                        case AUTHENTICATED:
                            Log.d(TAG, "onChanged: Auth success");
                            break;
                        case LOADING:
                            Log.d(TAG, "onChanged: Auth in progress");
                            break;
                        case NOT_AUTHENTICATED:
                            goToWelcomeScreen();
                            Log.d(TAG, "onChanged: Auth failed");
                            break;
                        case ERROR:
                            Log.d(TAG, "onChanged: Auth error");
                            break;
                    }
                }
            }
        });
    }
}

protected void goToWelcomeScreen() {
    Intent intent = new Intent(this, WelcomeActivity.class);
    finish();
    startActivity(intent);
}

这是我的会话管理器方法：

    private void initAuthedUser() {
        authedUser.setValue(AuthResource.loading((LoggedUser) null));
        final LiveData<LoggedUser> source = ribonyRepository.getAuthedUser();
        authedUser.setValue(AuthResource.notAuthenticated(null));
    }

    public LiveData<AuthResource<LoggedUser>> getAuthedUser() {
        return authedUser;
    }

如您所见，如果我运行观察者中的 goToWelcomeScreen 方法我的 activity 正在泄漏。这里泄漏日志：

LibraryLeak(className=com.impact.ribony.activities.MainNavigationActivity, leakTrace=
┬
├─ android.app.ActivityThread
│    Leaking: NO (a class is never leaking)
│    GC Root: System class
│    ↓ static ActivityThread.sCurrentActivityThread
│                            ~~~~~~~~~~~~~~~~~~~~~~
├─ android.app.ActivityThread
│    Leaking: UNKNOWN
│    ↓ ActivityThread.mNewActivities
│                     ~~~~~~~~~~~~~~
├─ android.app.ActivityThread$ActivityClientRecord
│    Leaking: UNKNOWN
│    ↓ ActivityThread$ActivityClientRecord.nextIdle
│                                          ~~~~~~~~
├─ android.app.ActivityThread$ActivityClientRecord
│    Leaking: UNKNOWN
│    ↓ ActivityThread$ActivityClientRecord.activity
│                                          ~~~~~~~~
╰→ com.impact.ribony.activities.MainNavigationActivity
     Leaking: YES (Activity#mDestroyed is true and ObjectWatcher was watching this)
     key = 4f1783be-bb8f-45df-96bb-e961b3277a1a
     watchDurationMillis = 5196
     retainedDurationMillis = 190
, retainedHeapByteSize=1213860, pattern=instance field android.app.ActivityThread$ActivityClientRecord#nextIdle, description=Android AOSP sometimes keeps a reference to a destroyed activity as a nextIdle client record in the android.app.ActivityThread.mActivities map. Not sure what's going on there, input welcome.)

有趣的是，如果我将 onCreate 更改为以下，那么我的 activity 不会泄漏。（我从 subscribeObservers 方法中删除了 goToWelcomeScreen 调用。）

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main_navigation);
    bottomNavigationView = findViewById(R.id.bottom_navigation);
    subscribeObservers();
    goToWelcomeScreen();
}

什么会导致这个问题？我该如何解决？

谢谢

Answer 1

首先按照下面的建议更改您的 goToWelcomeScreen 方法。

protected void goToWelcomeScreen() {
    Intent intent = new Intent(this, WelcomeActivity.class);
    startActivity(intent);        
    finish();
}

下次开始后调用 finish activity。您的 activity 泄漏的原因可能是因为 activity 似乎已完成，但实时数据观察器仍处于活动状态。您必须将 ViewModel 与实时数据一起使用，并将您的 activity 附加到视图模型的生命周期。

这样做可以确保所有活跃的 activity 观察者与 activity 一起被摧毁。

案例 2：在第二种情况下，activity 没有泄漏，因为在执行 sessionManager.getAuthedUser() 时，您的 activity 在附加观察者之前已经完成（因为goToWelcomeActivity 将在那时执行）。

希望它能帮助您消除疑虑，干杯！

Answer 2

这被 LeakCanary 识别为 "library leak"，这意味着它看起来像是 Android 框架中的已知泄漏。查看您粘贴的跟踪中的描述：

Android AOSP sometimes keeps a reference to a destroyed activity as a nextIdle client record in the android.app.ActivityThread.mActivities map. Not sure what's going on there, input welcome.

听起来您找到了解决问题的方法，这是很好的第一步。看起来，如果您在 onCreate() 期间切换活动，则不会出现问题，但实时数据引入了导致这种情况发生的延迟。

从实时数据更改 activity 导致内存泄漏

Changing activity from live data is causing memory leak

android

memory-leaks

leakcanary

android-livedata