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Leak Canary能够检测ViewPager2中TabLayout的内存泄漏问题。

androidmemory-leaksandroid-tablayoutleakcanary
19

我按照官方文档设置了一个带有ViewPager2的TabLayout。我使用了TabLayoutMediator这种方式将TabLayout与ViewPager2连接起来：

TabLayoutMediator(binding.tabLayout, binding.viewPager) { tab, position ->
        tab.setIcon(getTabIcon(position))
        tab.text = getTabTitle(position)
    }.attach()

然而，Leak Canary 检测到一个似乎与 TabLayout 和 TabLayoutMediator 相关的内存泄漏。 日志如下：

2020-05-13 17:57:32.914 D/LeakCanary: ┬───
2020-05-13 17:57:32.914 D/LeakCanary: │ GC Root: Local variable in native code
2020-05-13 17:57:32.914 D/LeakCanary: │
2020-05-13 17:57:32.914 D/LeakCanary: ├─ android.net.ConnectivityThread instance
2020-05-13 17:57:32.914 D/LeakCanary: │    Leaking: NO (PathClassLoader↓ is not leaking)
2020-05-13 17:57:32.914 D/LeakCanary: │    Thread name: 'ConnectivityThread'
2020-05-13 17:57:32.914 D/LeakCanary: │    ↓ ConnectivityThread.contextClassLoader
2020-05-13 17:57:32.914 D/LeakCanary: ├─ dalvik.system.PathClassLoader instance
2020-05-13 17:57:32.914 D/LeakCanary: │    Leaking: NO (ViewDataBinding↓ is not leaking and A ClassLoader is never leaking)
2020-05-13 17:57:32.914 D/LeakCanary: │    ↓ PathClassLoader.runtimeInternalObjects
2020-05-13 17:57:32.914 D/LeakCanary: ├─ java.lang.Object[] array
2020-05-13 17:57:32.914 D/LeakCanary: │    Leaking: NO (ViewDataBinding↓ is not leaking)
2020-05-13 17:57:32.914 D/LeakCanary: │    ↓ Object[].[349]
2020-05-13 17:57:32.914 D/LeakCanary: ├─ androidx.databinding.ViewDataBinding class
2020-05-13 17:57:32.914 D/LeakCanary: │    Leaking: NO (RouteInfoFragment↓ is not leaking and a class is never leaking)
2020-05-13 17:57:32.914 D/LeakCanary: │    ↓ static ViewDataBinding.sReferenceQueue
2020-05-13 17:57:32.914 D/LeakCanary: ├─ java.lang.ref.ReferenceQueue instance
2020-05-13 17:57:32.914 D/LeakCanary: │    Leaking: NO (RouteInfoFragment↓ is not leaking)
2020-05-13 17:57:32.914 D/LeakCanary: │    ↓ ReferenceQueue.head
2020-05-13 17:57:32.914 D/LeakCanary: ├─ androidx.databinding.ViewDataBinding$WeakListener instance
2020-05-13 17:57:32.914 D/LeakCanary: │    Leaking: NO (RouteInfoFragment↓ is not leaking)
2020-05-13 17:57:32.914 D/LeakCanary: │    ↓ ViewDataBinding$WeakListener.mObservable
2020-05-13 17:57:32.914 D/LeakCanary: ├─ androidx.databinding.ViewDataBinding$LiveDataListener instance
2020-05-13 17:57:32.914 D/LeakCanary: │    Leaking: NO (RouteInfoFragment↓ is not leaking)
2020-05-13 17:57:32.914 D/LeakCanary: │    ↓ ViewDataBinding$LiveDataListener.mLifecycleOwner
2020-05-13 17:57:32.914 D/LeakCanary: ├─ iclaude.berlinwanderer.features.route.ui.route_dashboard.route_info.RouteInfoFragment instance
2020-05-13 17:57:32.915 D/LeakCanary: │    Leaking: NO (RouteDashboardFragment↓ is not leaking and Fragment#mFragmentManager is not null)
2020-05-13 17:57:32.915 D/LeakCanary: │    Fragment.mTag=f0
2020-05-13 17:57:32.915 D/LeakCanary: │    ↓ RouteInfoFragment.mParentFragment
2020-05-13 17:57:32.915 D/LeakCanary: ├─ iclaude.berlinwanderer.features.route.ui.route_dashboard.RouteDashboardFragment instance
2020-05-13 17:57:32.915 D/LeakCanary: │    Leaking: NO (Fragment#mFragmentManager is not null)
2020-05-13 17:57:32.915 D/LeakCanary: │    ↓ RouteDashboardFragment.mLifecycleRegistry
2020-05-13 17:57:32.915 D/LeakCanary: │                             ~~~~~~~~~~~~~~~~~~
2020-05-13 17:57:32.915 D/LeakCanary: ├─ androidx.lifecycle.LifecycleRegistry instance
2020-05-13 17:57:32.915 D/LeakCanary: │    Leaking: UNKNOWN
2020-05-13 17:57:32.915 D/LeakCanary: │    ↓ LifecycleRegistry.mObserverMap
2020-05-13 17:57:32.915 D/LeakCanary: │                        ~~~~~~~~~~~~
2020-05-13 17:57:32.915 D/LeakCanary: ├─ androidx.arch.core.internal.FastSafeIterableMap instance
2020-05-13 17:57:32.915 D/LeakCanary: │    Leaking: UNKNOWN
2020-05-13 17:57:32.915 D/LeakCanary: │    ↓ FastSafeIterableMap.mHashMap
2020-05-13 17:57:32.915 D/LeakCanary: │                          ~~~~~~~~
2020-05-13 17:57:32.915 D/LeakCanary: ├─ java.util.HashMap instance
2020-05-13 17:57:32.915 D/LeakCanary: │    Leaking: UNKNOWN
2020-05-13 17:57:32.915 D/LeakCanary: │    ↓ HashMap.table
2020-05-13 17:57:32.915 D/LeakCanary: │              ~~~~~
2020-05-13 17:57:32.915 D/LeakCanary: ├─ java.util.HashMap$Node[] array
2020-05-13 17:57:32.915 D/LeakCanary: │    Leaking: UNKNOWN
2020-05-13 17:57:32.915 D/LeakCanary: │    ↓ HashMap$Node[].[1]
2020-05-13 17:57:32.915 D/LeakCanary: │                     ~~~
2020-05-13 17:57:32.915 D/LeakCanary: ├─ java.util.HashMap$Node instance
2020-05-13 17:57:32.915 D/LeakCanary: │    Leaking: UNKNOWN
2020-05-13 17:57:32.915 D/LeakCanary: │    ↓ HashMap$Node.key
2020-05-13 17:57:32.915 D/LeakCanary: │                   ~~~
2020-05-13 17:57:32.915 D/LeakCanary: ├─ androidx.viewpager2.adapter.FragmentStateAdapter$5 instance
2020-05-13 17:57:32.915 D/LeakCanary: │    Leaking: UNKNOWN
2020-05-13 17:57:32.915 D/LeakCanary: │    Anonymous class implementing androidx.lifecycle.LifecycleEventObserver
2020-05-13 17:57:32.915 D/LeakCanary: │    ↓ FragmentStateAdapter$5.this$0
2020-05-13 17:57:32.916 D/LeakCanary: │                             ~~~~~~
2020-05-13 17:57:32.916 D/LeakCanary: ├─ iclaude.berlinwanderer.features.route.ui.route_dashboard.RouteDashboardViewPagerAdapter instance
2020-05-13 17:57:32.916 D/LeakCanary: │    Leaking: UNKNOWN
2020-05-13 17:57:32.916 D/LeakCanary: │    ↓ RouteDashboardViewPagerAdapter.mObservable
2020-05-13 17:57:32.916 D/LeakCanary: │                                     ~~~~~~~~~~~
2020-05-13 17:57:32.916 D/LeakCanary: ├─ androidx.recyclerview.widget.RecyclerView$AdapterDataObservable instance
2020-05-13 17:57:32.916 D/LeakCanary: │    Leaking: UNKNOWN
2020-05-13 17:57:32.916 D/LeakCanary: │    ↓ RecyclerView$AdapterDataObservable.mObservers
2020-05-13 17:57:32.916 D/LeakCanary: │                                         ~~~~~~~~~~
2020-05-13 17:57:32.916 D/LeakCanary: ├─ java.util.ArrayList instance
2020-05-13 17:57:32.916 D/LeakCanary: │    Leaking: UNKNOWN
2020-05-13 17:57:32.916 D/LeakCanary: │    ↓ ArrayList.elementData
2020-05-13 17:57:32.916 D/LeakCanary: │                ~~~~~~~~~~~
2020-05-13 17:57:32.916 D/LeakCanary: ├─ java.lang.Object[] array
2020-05-13 17:57:32.916 D/LeakCanary: │    Leaking: UNKNOWN
2020-05-13 17:57:32.916 D/LeakCanary: │    ↓ Object[].[0]
2020-05-13 17:57:32.916 D/LeakCanary: │               ~~~
2020-05-13 17:57:32.916 D/LeakCanary: ├─ com.google.android.material.tabs.TabLayoutMediator$PagerAdapterObserver instance
2020-05-13 17:57:32.916 D/LeakCanary: │    Leaking: UNKNOWN
2020-05-13 17:57:32.916 D/LeakCanary: │    ↓ TabLayoutMediator$PagerAdapterObserver.this$0
2020-05-13 17:57:32.916 D/LeakCanary: │                                             ~~~~~~
2020-05-13 17:57:32.916 D/LeakCanary: ├─ com.google.android.material.tabs.TabLayoutMediator instance
2020-05-13 17:57:32.916 D/LeakCanary: │    Leaking: UNKNOWN
2020-05-13 17:57:32.916 D/LeakCanary: │    ↓ TabLayoutMediator.tabLayout
2020-05-13 17:57:32.916 D/LeakCanary: │                        ~~~~~~~~~
2020-05-13 17:57:32.916 D/LeakCanary: ├─ com.google.android.material.tabs.TabLayout instance
2020-05-13 17:57:32.916 D/LeakCanary: │    Leaking: YES (View detached and has parent)
2020-05-13 17:57:32.916 D/LeakCanary: │    mContext instance of iclaude.berlinwanderer.features.route.ui.RouteActivity with mDestroyed = false
2020-05-13 17:57:32.916 D/LeakCanary: │    View#mParent is set
2020-05-13 17:57:32.916 D/LeakCanary: │    View#mAttachInfo is null (view detached)
2020-05-13 17:57:32.916 D/LeakCanary: │    View.mID = R.id.tab_layout
2020-05-13 17:57:32.916 D/LeakCanary: │    View.mWindowAttachCount = 1
2020-05-13 17:57:32.916 D/LeakCanary: │    ↓ TabLayout.mParent
2020-05-13 17:57:32.916 D/LeakCanary: ╰→ androidx.constraintlayout.motion.widget.MotionLayout instance
2020-05-13 17:57:32.916 D/LeakCanary: ​     Leaking: YES (ObjectWatcher was watching this because iclaude.berlinwanderer.features.route.ui.route_dashboard.RouteDashboardFragment received Fragment#onDestroyView() callback (references to its views should be cleared to prevent leaks))
2020-05-13 17:57:32.916 D/LeakCanary: ​     key = 9c28ffc6-b1ce-4316-b015-c4df278892a1
2020-05-13 17:57:32.916 D/LeakCanary: ​     watchDurationMillis = 36154
2020-05-13 17:57:32.916 D/LeakCanary: ​     retainedDurationMillis = 31130
2020-05-13 17:57:32.916 D/LeakCanary: ​     mContext instance of iclaude.berlinwanderer.features.route.ui.RouteActivity with mDestroyed = false
2020-05-13 17:57:32.917 D/LeakCanary: ​     View#mParent is null
2020-05-13 17:57:32.917 D/LeakCanary: ​     View#mAttachInfo is null (view detached)
2020-05-13 17:57:32.917 D/LeakCanary: ​     View.mID = R.id.ml_main
2020-05-13 17:57:32.917 D/LeakCanary: ​     View.mWindowAttachCount = 1

问题出在哪里？如何解决？

4个回答
33
我认为这是一个错误，在Google上有记录。 https://issuetracker.google.com/issues/151212195 https://issuetracker.google.com/issues/154751401 评论中提到了一个解决方案，对我来说似乎起作用了。使您的FragmentStateAdapter使用构造函数。
 public FragmentStateAdapter(@NonNull FragmentManager fragmentManager,
            @NonNull Lifecycle lifecycle) {

从您的容器片段创建适配器如下：

FragmentManager fm = getChildFragmentManager();
Lifecycle lifecycle = getViewLifecycleOwner().getLifecycle();
fragmentAdapter = new FragmentAdapter(fm, lifecycle);
3
到目前为止，这是最好的解决方案。最佳实践仍然建议在Fragment的onDestroyView()方法中调用TabLayoutMediator的detach()方法，但是这种解决方案避免了手动将实例设置为null的需要。 - Martin
2
我一直在使用FragmentStateAdapter(Fragment fragment)构造函数，该构造函数又调用了你提到的构造函数。但重要的区别是它是使用片段的生命周期而不是视图的生命周期进行调用的。当我明确传递viewLifecycleOwner时，泄漏问题就消失了。 - Oleksii Urusov
这只发生在使用Fragment时吗？还是在使用Activity时也会发生？ - Undefined function
11

您需要在onDestroyView中解除绑定并将中介者设置为null：

class YourFragment: Fragment() {
    
    private var mediator: TabLayoutMediator? = null

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        mediator = TabLayoutMediator(binding.tabLayout, binding.viewPager) { tab, position ->
            tab.setIcon(getTabIcon(position))
            tab.text = getTabTitle(position)
        }
        mediator.attach()
    }

    override fun onDestroyView() {
        super.onDestroyView()
        mediator?.detach()
        mediator = null
        binding.viewpager.adapter = null
        _binding = null
    }

}
2

我曾经遇到类似的问题，你需要在onDestroyView方法中将viewPager适配器设置为null，如果你使用了数据绑定，确保将绑定设置为null。祝你好运。

1
我找到了一个解决方案。看起来在onDestroyView中，你必须将viewpager.adaper字段、适配器本身、TabLauoutMediator（在分离后）和绑定类引用设置为null。希望官方文档在未来变得更加清晰明了。 - iClaude
0

你的mContext是由RouteActivity暴露出来的，即使RouteActivity被销毁（或重新创建），它仍然存在。这可能是因为有些东西正在使用它。跟踪使用mContext的内容并停止它。

RouteActivity是持有Fragments的Activity，因此它不会被销毁或重新创建。 - iClaude
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