android P版本 系统稳定性问题案例分析(一)

一、无锁状态下，灭屏后亮屏设置界面滑动无效。

问题分析：

（1）可在其他应用界面复现，非应用问题。

（2）问题必现，点击动作有效但无动画效果，滑动后界面不刷新但可确认对应位置在后台已发生变化，非输入系统错误。

（3）滑动后界面没有刷新，截图后与当前设备显示相同，排除显示系统的硬件问题，为显示系统的软件问题。

 

问题排查：

（1）根据绘制流程添加log分析。performTraversals（performMeasure，performLayout，performDraw），此处没有问题。

（2）分析performDraw流程添加log分析。performDraw（ViewTreeObserver.draw()/drawSoftware），发现performDraw正常运行，ViewTreeObserver.draw()在出现问题后不再调用。

（３）根据（２），继续追查问题发现ViewRootImpl.draw()中[surface.isValid()＝true]，进而追踪surface无效的原因。

（４）根据代码发现每次灭屏后会调用ViewRootImpl.setWindowStopped(true)进而都会mSurface.release()。

（５）亮屏由于没有锁屏界面，灭屏时的界面没有发生任何变化且非第一绘制，不会重新使能surface。

    void setWindowStopped(boolean stopped) {
        if (mStopped != stopped) {
            mStopped = stopped;
            final ThreadedRenderer renderer = mAttachInfo.mThreadedRenderer;
            if (renderer != null) {
                if (DEBUG_DRAW) Log.d(mTag, "WindowStopped on " + getTitle() + " set to " + mStopped);
                renderer.setStopped(mStopped);
            }
            if (!mStopped) {
                scheduleTraversals();
            } else {
                if (renderer != null) {
                    renderer.destroyHardwareResources(mView);
                }
            }

            for (int i = 0; i < mWindowStoppedCallbacks.size(); i++) {
                mWindowStoppedCallbacks.get(i).windowStopped(stopped);
            }

            if (mStopped) {
                mSurface.release();
            }
        }
    }

问题总结：

此问题是由于灭屏后mSurface.release()，而亮屏时没有触发重现使能surface而导致的。

 

二、桌面有手势按键（quickstep）的时候，出现桌面anr事件：

----- pid 10005 at 2019-01-01 12:22:46 -----
Cmd line: com.android.launcher3

"main" prio=5 tid=1 Blocked
  | group="main" sCount=1 dsCount=0 flags=1 obj=0x75e5fab0 self=0x70f3a14c00
  | sysTid=10005 nice=-10 cgrp=default sched=0/0 handle=0x717a1b5548
  | state=S schedstat=( 481187776 24084236 354 ) utm=39 stm=8 core=1 HZ=100
  | stack=0x7ffbeae000-0x7ffbeb0000 stackSize=8MB
  | held mutexes=
  at com.android.quickstep.NormalizedIconLoader.getBitmapInfo(NormalizedIconLoader.java:-1)
  - waiting to lock <0x0b405da7> (a com.android.quickstep.NormalizedIconLoader) held by thread 10
  at com.android.quickstep.NormalizedIconLoader.getDefaultIcon(NormalizedIconLoader.java:58)
  - locked <0x0d1af254> (a android.util.SparseArray)
  at com.android.systemui.shared.recents.model.RecentsTaskLoader.loadTaskData(RecentsTaskLoader.java:185)
  at com.android.quickstep.views.RecentsView.loadVisibleTaskData(RecentsView.java:672)
  at com.android.quickstep.views.RecentsView.resetTaskVisuals(RecentsView.java:567)
  at com.android.quickstep.views.RecentsView.applyLoadPlan(RecentsView.java:543)
  at com.android.quickstep.views.RecentsView.lambda$w02bBzSWizaR4dIzSj9kQ73I7BA(RecentsView.java:-1)
  at com.android.quickstep.views.-$$Lambda$RecentsView$w02bBzSWizaR4dIzSj9kQ73I7BA.accept(lambda:-1)
  at com.android.quickstep.RecentsModel.lambda$loadTasks$1(RecentsModel.java:142)
  at com.android.quickstep.-$$Lambda$RecentsModel$rZAN1-eRHSYycmOWL-UzK9dzJ1Q.run(lambda:-1)
  at com.android.launcher3.util.LooperExecutor.execute(LooperExecutor.java:43)
  at com.android.quickstep.RecentsModel.loadTasks(RecentsModel.java:142)
  at com.android.quickstep.views.RecentsView.setCurrentTask(RecentsView.java:775)
  at com.android.quickstep.views.RecentsView.showTask(RecentsView.java:745)
  at com.android.quickstep.WindowTransformSwipeHandler.onLauncherStart(WindowTransformSwipeHandler.java:409)
  at com.android.quickstep.WindowTransformSwipeHandler.lambda$oTmdTx9KEnt4AhNDszi5oKfUOY4(WindowTransformSwipeHandler.java:-1)
  at com.android.quickstep.-$$Lambda$WindowTransformSwipeHandler$oTmdTx9KEnt4AhNDszi5oKfUOY4.onActivityStart(lambda:-1)
  at com.android.launcher3.BaseDraggingActivity.onStart(BaseDraggingActivity.java:235)
  at com.android.launcher3.Launcher.onStart(Launcher.java:848)
  at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1391)
  at android.app.Activity.performStart(Activity.java:7157)
  at android.app.ActivityThread.handleStartActivity(ActivityThread.java:2968)
  at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java:180)
  at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:165)
  at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:142)
  at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:70)
  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1836)
  at android.os.Handler.dispatchMessage(Handler.java:106)
  at android.os.Looper.loop(Looper.java:193)
  at android.app.ActivityThread.main(ActivityThread.java:6702)
  at java.lang.reflect.Method.invoke(Native method)
  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:911)


"Binder:10005_3" prio=5 tid=10 Waiting
  | group="main" sCount=1 dsCount=0 flags=1 obj=0x12e04f78 self=0x70ed23c000
  | sysTid=10018 nice=0 cgrp=default sched=0/0 handle=0x70debee4f0
  | state=S schedstat=( 51705932 1946846 88 ) utm=2 stm=2 core=2 HZ=100
  | stack=0x70deaf3000-0x70deaf5000 stackSize=1009KB
  | held mutexes=
  at java.lang.Object.wait(Native method)
  - waiting on <0x095edfc0> (a java.lang.Object)
  at java.lang.Thread.parkFor$(Thread.java:2137)
  - locked <0x095edfc0> (a java.lang.Object)
  at sun.misc.Unsafe.park(Unsafe.java:358)
  at java.util.concurrent.locks.LockSupport.park(LockSupport.java:190)
  at java.util.concurrent.FutureTask.awaitDone(FutureTask.java:450)
  at java.util.concurrent.FutureTask.get(FutureTask.java:192)
  at com.android.launcher3.LauncherAppState.getInstance(LauncherAppState.java:66)
  at com.android.launcher3.LauncherAppState.getIDP(LauncherAppState.java:174)
  at com.android.launcher3.graphics.LauncherIcons.(LauncherIcons.java:133)
  at com.android.launcher3.graphics.LauncherIcons.obtain(LauncherIcons.java:91)
  at com.android.quickstep.NormalizedIconLoader.getBitmapInfo(NormalizedIconLoader.java:76)
  - locked <0x0b405da7> (a com.android.quickstep.NormalizedIconLoader)
  at com.android.quickstep.NormalizedIconLoader.getBadgedActivityIcon(NormalizedIconLoader.java:88)
  at com.android.systemui.shared.recents.model.IconLoader.createNewIconForTask(IconLoader.java:134)
  at com.android.systemui.shared.recents.model.IconLoader.getAndInvalidateIfModified(IconLoader.java:94)
  at com.android.systemui.shared.recents.model.RecentsTaskLoader.getAndUpdateActivityIcon(RecentsTaskLoader.java:325)
  at com.android.systemui.shared.recents.model.RecentsTaskLoadPlan.executePlan(RecentsTaskLoadPlan.java:182)
  at com.android.systemui.shared.recents.model.RecentsTaskLoader.loadTasks(RecentsTaskLoader.java:173)
  - locked <0x0411f4f9> (a com.android.quickstep.RecentsModel$1)
  at com.android.quickstep.RecentsModel.onTaskStackChangedBackground(RecentsModel.java:214)
  at com.android.systemui.shared.system.TaskStackChangeListeners.onTaskStackChanged(TaskStackChangeListeners.java:79)
  at android.app.ITaskStackListener$Stub.onTransact(ITaskStackListener.java:50)
  at android.os.Binder.execTransact(Binder.java:731)

问题分析：

从anr文件上来看是
(1)线程"Binder:10005_3" locked <0x0b405da7> (a com.android.quickstep.NormalizedIconLoader)
(2)主线程"main" waiting to lock <0x0b405da7> (a com.android.quickstep.NormalizedIconLoader) held by thread 1

那么可以确认是由于线程"Binder:10005_3"运行时间过长而导致的UI线程出现ANR的。

进一步分析"Binder:10005_3"发现，"Binder:10005_3"是在运行LauncherAppState.getInstance耗时太长造成的，而耗时太长的原因是由于线程使用FutureTask属性在阻塞等待其他线程的唤醒，而等待的线程是那个呢？我们看下LauncherAppState.getInstance的代码：

    public static LauncherAppState getInstance(final Context context) {
        if (INSTANCE == null) {
            if (Looper.myLooper() == Looper.getMainLooper()) {
                INSTANCE = new LauncherAppState(context.getApplicationContext());
            } else {
                try {
                    return new MainThreadExecutor().submit(new Callable() {
                        @Override
                        public LauncherAppState call() throws Exception {
                            return LauncherAppState.getInstance(context);
                        }
                    }).get();
                } catch (InterruptedException|ExecutionException e) {
                    throw new RuntimeException(e);
                }
            }
        }
        return INSTANCE;
    }

从上面函数可以看到LauncherAppState是一个典型的单例模式，而它的创建被限制在了UI线程中，也就是说只有UI线程才能创建这个单例模式的LauncherAppState，而线程"Binder:10005_3"创建时需要用到MainThreadExecutor去阻塞的等待主线程"main"创建完成之后才能继续运行（此处使用了Future类并发编程模型）。而主线程"main"此时却在等待着线程"Binder:10005_3"一直locked的锁 <0x0b405da7>，而此行为也导致了主线程"main"的Loop流程阻塞，进而导致线程"Binder:10005_3"永远无法拿到LauncherAppState的实现。

问题流程图如下：

 

android P版本 系统稳定性问题案例分析(二)