java - 由于 AccessibilityNodeInfo getChild 而导致大量 ANR

Question

收到大量 ANR 报告，

"main" prio=5 tid=1 Runnable | group="main" sCount=0 dsCount=0 flags=0 obj=0x72e8a568 self=0xe65da000 | sysTid=20592 nice=0 cgrp=default sched=0/0 handle=0xe9f6b4a8 | state=R schedstat=( 35792446568 9751828904 97371 ) utm=2328 stm=1249 core=2 HZ=100 | stack=0xff6e5000-0xff6e7000 stackSize=8MB | held mutexes= "mutator lock"(shared held) native: pc 00000000002c45b7 /system/lib/libart.so (_ZN3art15DumpNativeStackERNSt3__113basic_ostreamIcNS0_11char_traitsIcEEEEiP12BacktraceMapPKcPNS_9ArtMethodEPv+130) native: pc 0000000000355a83 /system/lib/libart.so (_ZNK3art6Thread9DumpStackERNSt3__113basic_ostreamIcNS1_11char_traitsIcEEEEbP12BacktraceMapb+202) native: pc 0000000000351f67 /system/lib/libart.so (_ZNK3art6Thread4DumpERNSt3__113basic_ostreamIcNS1_11char_traitsIcEEEEbP12BacktraceMapb+34) native: pc 00000000003698df /system/lib/libart.so (_ZN3art14DumpCheckpoint3RunEPNS_6ThreadE+654) native: pc 000000000035662b /system/lib/libart.so (_ZN3art6Thread21RunCheckpointFunctionEv+298) native: pc 00000000003bbcff /system/lib/libart.so (_ZN3art16JniMethodFastEndEjPNS_6ThreadE+46) native: pc 0000000000403fdb /system/framework/arm/boot-framework.oat (Java_android_os_Parcel_nativeReadInt__J+114) at android.os.Parcel.nativeReadInt (Native method) at android.os.Parcel.readInt (Parcel.java:1966) at android.os.Parcel.readExceptionCode (Parcel.java:1906) at android.os.Parcel.readException (Parcel.java:1885) at android.accessibilityservice.IAccessibilityServiceConnection$Stub$Proxy.findAccessibilityNodeInfoByAccessibilityId (IAccessibilityServiceConnection.java:447) at android.view.accessibility.AccessibilityInteractionClient.findAccessibilityNodeInfoByAccessibilityId (AccessibilityInteractionClient.java:286) at android.view.accessibility.AccessibilityNodeInfo.getChild (AccessibilityNodeInfo.java:959) at MyAccessibilityService.traverseNode (MyAccessibilityService.java:94) at MyAccessibilityService.traverseNode (MyAccessibilityService.java:100) at MyAccessibilityService.traverseNode (MyAccessibilityService.java:100) at MyAccessibilityService.traverseNode (MyAccessibilityService.java:100) at MyAccessibilityService.collectTextNodes (MyAccessibilityService.java:69) at MyAccessibilityService.onAccessibilityEvent (MyAccessibilityService.java:384) at android.accessibilityservice.AccessibilityService$2.onAccessibilityEvent (AccessibilityService.java:1527) at android.accessibilityservice.AccessibilityService$IAccessibilityServiceClientWrapper.executeMessage (AccessibilityService.java:1712) at com.android.internal.os.HandlerCaller$MyHandler.handleMessage (HandlerCaller.java:37)

    "main" prio=5 tid=1 Native
      | group="main" sCount=1 dsCount=0 flags=1 obj=0x72e8a568 self=0xe65da000
      | sysTid=11518 nice=0 cgrp=default sched=0/0 handle=0xe9f6b4a8
      | state=S schedstat=( 34572861602 18459176949 199877 ) utm=2350 stm=1106 core=1 HZ=100
      | stack=0xff6e5000-0xff6e7000 stackSize=8MB
      | held mutexes=
      native: pc 0000000000018dac  /system/lib/libc.so (syscall+28)
      native: pc 00000000000b3729  /system/lib/libart.so (_ZN3art17ConditionVariable16WaitHoldingLocksEPNS_6ThreadE+88)
      native: pc 00000000003bbbe3  /system/lib/libart.so (_ZN3artL12GoToRunnableEPNS_6ThreadE+306)
      native: pc 00000000003bba81  /system/lib/libart.so (_ZN3art12JniMethodEndEjPNS_6ThreadE+8)
      native: pc 00000000007ca401  /system/framework/arm/boot-framework.oat (Java_android_os_BinderProxy_transactNative__ILandroid_os_Parcel_2Landroid_os_Parcel_2I+144)
      at android.os.BinderProxy.transactNative (Native method)
      at android.os.BinderProxy.transact (Binder.java:748)
      at android.accessibilityservice.IAccessibilityServiceConnection$Stub$Proxy.findAccessibilityNodeInfoByAccessibilityId (IAccessibilityServiceConnection.java:446)
      at android.view.accessibility.AccessibilityInteractionClient.findAccessibilityNodeInfoByAccessibilityId (AccessibilityInteractionClient.java:286)
      at android.view.accessibility.AccessibilityNodeInfo.getChild (AccessibilityNodeInfo.java:959)
      at MyAccessibilityService.traverseNode (MyAccessibilityService.java:94)
      at MyAccessibilityService.traverseNode (MyAccessibilityService.java:100)
      at MyAccessibilityService.traverseNode (MyAccessibilityService.java:100)
      at MyAccessibilityService.traverseNode (MyAccessibilityService.java:100)
      at MyAccessibilityService.collectTextNodes (MyAccessibilityService.java:69)
      at MyAccessibilityService.onAccessibilityEvent (MyAccessibilityService.java:384)
      at android.accessibilityservice.AccessibilityService$2.onAccessibilityEvent (AccessibilityService.java:1527)
      at android.accessibilityservice.AccessibilityService$IAccessibilityServiceClientWrapper.executeMessage (AccessibilityService.java:1712)
      at com.android.internal.os.HandlerCaller$MyHandler.handleMessage (HandlerCaller.java:37)
      at android.os.Handler.dispatchMessage (Handler.java:105)


    "main" prio=5 tid=1 Runnable
      | group="main" sCount=0 dsCount=0 flags=0 obj=0x73bf7568 self=0xe7445000
      | sysTid=18941 nice=0 cgrp=default sched=0/0 handle=0xeae2e4a8
      | state=R schedstat=( 169234820933 190791369297 635928 ) utm=11752 stm=5170 core=0 HZ=100
      | stack=0xff795000-0xff797000 stackSize=8MB
      | held mutexes= "mutator lock"(shared held)
      at java.util.ArrayList.clear (ArrayList.java:565)
      at android.view.accessibility.AccessibilityNodeInfo.init (AccessibilityNodeInfo.java:3211)
      at android.view.accessibility.AccessibilityNodeInfo.obtain (AccessibilityNodeInfo.java:3015)
      at android.view.accessibility.AccessibilityCache.getNode (AccessibilityCache.java:231)
    - locked <0x0f41ae94> (a java.lang.Object)
      at android.view.accessibility.AccessibilityInteractionClient.findAccessibilityNodeInfoByAccessibilityId (AccessibilityInteractionClient.java:272)
      at android.view.accessibility.AccessibilityNodeInfo.getChild (AccessibilityNodeInfo.java:959)
      at MyAccessibilityService.traverseNode (MyAccessibilityService.java:84)
      at MyAccessibilityService.traverseNode (MyAccessibilityService.java:85)
      at MyAccessibilityService.traverseNode (MyAccessibilityService.java:85)
      at MyAccessibilityService.traverseNode (MyAccessibilityService.java:85)
      at MyAccessibilityService.collectTextNodes (MyAccessibilityService.java:66)
      at MyAccessibilityService.onAccessibilityEvent (MyAccessibilityService.java:360)
      at android.accessibilityservice.AccessibilityService$2.onAccessibilityEvent (AccessibilityService.java:1527)
      at android.accessibilityservice.AccessibilityService$IAccessibilityServiceClientWrapper.executeMessage (AccessibilityService.java:1712)
      at com.android.internal.os.HandlerCaller$MyHandler.handleMessage (HandlerCaller.java:37)
      at android.os.Handler.dispatchMessage (Handler.java:105)

"main" prio=5 tid=1 TimedWaiting
  | group="main" sCount=1 dsCount=0 flags=1 obj=0x73228568 self=0xed55a000
  | sysTid=19996 nice=0 cgrp=default sched=0/0 handle=0xed8414a8
  | state=S schedstat=( 39022541552 53623486893 130046 ) utm=3252 stm=648 core=2 HZ=100
  | stack=0xff636000-0xff638000 stackSize=8MB
  | held mutexes=
  at java.lang.Object.wait (Native method)
- waiting on <0x0b44b730> (a java.lang.Object)
  at java.lang.Object.wait (Object.java:422)
  at android.view.accessibility.AccessibilityInteractionClient.waitForResultTimedLocked (AccessibilityInteractionClient.java:687)
  at android.view.accessibility.AccessibilityInteractionClient.getFindAccessibilityNodeInfosResultAndClear (AccessibilityInteractionClient.java:582)
- locked <0x0b44b730> (a java.lang.Object)
  at android.view.accessibility.AccessibilityInteractionClient.findAccessibilityNodeInfoByAccessibilityId (AccessibilityInteractionClient.java:291)
  at android.view.accessibility.AccessibilityInteractionClient.getRootInActiveWindow (AccessibilityInteractionClient.java:160)
  at android.accessibilityservice.AccessibilityService.getRootInActiveWindow (AccessibilityService.java:572)
  at MyAccessibilityService.onAccessibilityEvent (MyAccessibilityService.java:370)

我的代码

ArrayList<AccessibilityNodeInfo> collectNodes(AccessibilityNodeInfo node) {

    ArrayList<AccessibilityNodeInfo> nodeInfoArrayList = new ArrayList<>();
    try {
        int childCount = node.getChildCount();
        for (int index = 0; index < childCount; index++) {
            AccessibilityNodeInfo childNode = node.getChild(index);


            traverseNode(childNode);
            if (childNodes != null && childNodes.size() > 0) {
                nodeInfoArrayList.addAll(childNodes);
                childNodes.clear();
            }
        }
    }
    catch (Exception e){
        e.printStackTrace();
    }
    return nodeInfoArrayList;
}

private void traverseNode(AccessibilityNodeInfo node) {
    try {
        AccessibilityNodeInfo edittextNode = null;
        if (null == node)
            return;

        final int count = node.getChildCount();
        if (count > 0) {
            for (int i = 0; i < count; i++) {
                AccessibilityNodeInfo childNode = node.getChild(i);
                if (childNode == null) {
                    node.recycle();
                    return;
                }
                else {
                    traverseNode(childNode);
                }
            }
        } else {

        }
    }
    catch (Exception error){
        error.printStackTrace();
    }
}

Android 8.0 中的更多问题。知道如何处理这些 ANR。

配置文件

<accessibility-service
    xmlns:android="http://schemas.android.com/apk/res/android"

    android:accessibilityEventTypes="typeWindowStateChanged|typeViewFocused|typeWindowContentChanged"

    android:notificationTimeout="100"
    android:canRetrieveWindowContent="true"

    android:accessibilityFeedbackType="feedbackGeneric"
    android:accessibilityFlags="flagReportViewIds|flagRequestEnhancedWebAccessibility"
    android:description="Test"/>

请注意几乎所有来自 Android 8.0 设备的 ANR 报告。

Answer 1

1. 首要的事情是回收所有由getChild、findAccessibilityNodeInfoByAccessibilityId 或任何其他函数分配的节点。所以你应该有这样的东西:

AccessibilityNodeInfo findFirstViewByText(AccessibilityNodeInfo rootNode, String text) {
        if (rootNode == null) return null;
        if (rootNode.getText() != null && rootNode.getText().toString().equals(text))
            return rootNode;
        int childCount = rootNode.getChildCount();
        for (int i = 0; i < childCount; i++) {
            AccessibilityNodeInfo tmpNode = rootNode.getChild(i);
            if (tmpNode != null) {
                AccessibilityNodeInfo res = findFirstViewByText(tmpNode, text);
                if (res != null) {
                    return res;
                } else {
                    tmpNode.recycle();
                }
            }
        }
        return null;
    }
}

node = findFirstViewByText(rootNode, "something");
if(node != null) {
  node.performAction(AccessibilityNodeInfo.ACTION_CLICK);
  node.recycle();
}

1. 请记住，当您与目标应用程序交互时，onAccessibilityEvent 可能会被过于频繁地调用，而且您在此函数中的处理会阻塞目标应用程序上的 UI 线程。您可以通过以下方式克服此问题:

   • 限制对 onAccessibilityEvent 的调用，即如果最后一次执行发生在 x 毫秒前，则不要执行您的代码，但要确保最后一次调用会触发代码的执行。
   • 通过避免不必要的遍历来提高代码的性能。定义状态，以便应用仅查找与当前状态相关的节点。

2. 随时分享您的更多代码，以便我/我们能够了解您的目标，这样我们就可以提供更多帮助。正如我从您的日志中看到的那样，有几个线程遍历无障碍服务的虚拟 dom，它们导致了死锁。