使用 OutOfMemoryException 调用订阅者 onError() 时出现 IllegalStateException

Question

我的代码旨在拍摄原始图像，异步处理它，并让用户看到他们处理过的图像。有时，图像处理会导致 OutOfMemory 错误，然后我想通知用户他们的设备内存不足。

但是，在尝试捕获错误并通知订阅者时，我遇到了崩溃。此外，当我在代码中放置断点时，会捕获 OutOfMemory 错误，并命中 subscriber.onError(e) 行，但从未达到 onPhotoProcessingError(e)。

这里是订阅发生的地方：

imageDelegate.cropBitmap(rawPhoto, cameraManager.getPictureRotationDegrees(), cameraManager.getCurrentCameraId() == Camera.CameraInfo.CAMERA_FACING_FRONT)
            .subscribeOn(Schedulers.computation())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(new Subscriber<Bitmap>() {
                @Override
                public void onNext(Bitmap bitmap)
                {
                    onPhotoProcessed(bitmap);
                }

                @Override
                public void onError(Throwable e)
                {
                    onPhotoProcessingError(e);
                }

                @Override
                public void onCompleted()
                {

                }
            });

下面是捕获 OutOfMemory 错误的代码：

public Observable<Bitmap> cropBitmap(Bitmap rawPhoto, int rotation, boolean isFrontFacing)
{
    return Observable.create(new Observable.OnSubscribe<Bitmap>()
    {
        @Override
        public void call(Subscriber<? super Bitmap> subscriber)
        {
            try
            {
                // rotates the photo so that it's portrait and cuts off the
                // bottom of the photo so that we have a square photo
                Bitmap rotatedSquarePhoto = PhotoUtils.rotateAndTruncateBottomOfPictureIntoSquare(rawPhoto, rotation);
                rawPhoto.recycle();

                // we want to mirror the image to match what the user saw when taking a selfie
                if (isFrontFacing)
                {
                    rotatedSquarePhoto = PhotoUtils.reflectAboutYAxis(rotatedSquarePhoto);
                }

                subscriber.onNext(rotatedSquarePhoto);
            }
            catch (OutOfMemoryError e)
            {
                subscriber.onError(e);
            }
        }
    });
}

这里是崩溃的堆栈跟踪：

    04-06 16:40:55.303 22729-22729/ E/AndroidRuntime: FATAL EXCEPTION: main
   Process: com.emersonboyd, PID: 22729
   java.lang.IllegalStateException: Fatal Exception thrown on Scheduler.Worker thread.
       at rx.internal.schedulers.ScheduledAction.run(ScheduledAction.java:62)
       at android.os.Handler.handleCallback(Handler.java:751)
       at android.os.Handler.dispatchMessage(Handler.java:95)
       at android.os.Looper.loop(Looper.java:154)
       at android.app.ActivityThread.main(ActivityThread.java:6119)
       at java.lang.reflect.Method.invoke(Native Method)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
    Caused by: java.lang.OutOfMemoryError: Failed to allocate a 921612 byte allocation with 861608 free bytes and 841KB until OOM
       at dalvik.system.VMRuntime.newNonMovableArray(Native Method)
       at android.graphics.Bitmap.nativeCreate(Native Method)
       at android.graphics.Bitmap.createBitmap(Bitmap.java:879)
       at android.graphics.Bitmap.createBitmap(Bitmap.java:856)
       at android.graphics.Bitmap.createBitmap(Bitmap.java:787)
       at com.emersonboyd.util.PhotoUtils.rotateAndTruncateBottomOfPictureIntoSquare(PhotoUtils.java:225)
       at com.emersonboyd.delgate.ImageDelegate.call(ImageDelegate.java:124)
       at com.emersonboyd.delgate.ImageDelegate.call(ImageDelegate.java:116)
       at rx.Observable.unsafeSubscribe(Observable.java:8460)
       at rx.internal.operators.OperatorSubscribeOn.call(OperatorSubscribeOn.java:94)
       at rx.internal.schedulers.EventLoopsScheduler$EventLoopWorker.call(EventLoopsScheduler.java:169)
       at rx.internal.schedulers.ScheduledAction.run(ScheduledAction.java:55)
       at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:428)
       at java.util.concurrent.FutureTask.run(FutureTask.java:237)
       at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:272)
       at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
       at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
       at java.lang.Thread.run(Thread.java:761)

如果能帮我指明正确的方向，那就太好了。

Answer 1

这是因为 OutOfMemoryError 被 RxJava 视为 致命错误。此类错误不是 "swallowed" 内部的，也不会传递给 onError 回调。

这是 RxJava1 源代码的片段。在每个内部错误处理块的开头调用此方法：

public static void throwIfFatal(Throwable t) {
    if (t instanceof OnErrorNotImplementedException) {
        throw (OnErrorNotImplementedException) t;
    } else if (t instanceof OnErrorFailedException) {
        throw (OnErrorFailedException) t;
    } else if (t instanceof OnCompletedFailedException) {
        throw (OnCompletedFailedException) t;
    }
    // values here derived from https://github.com/ReactiveX/RxJava/issues/748#issuecomment-32471495
    else if (t instanceof VirtualMachineError) {
        throw (VirtualMachineError) t;
    } else if (t instanceof ThreadDeath) {
        throw (ThreadDeath) t;
    } else if (t instanceof LinkageError) {
        throw (LinkageError) t;
    }
}

OutOfMemoryError 是 VirtualMachineError.

的后代

更多信息： https://github.com/ReactiveX/RxJava/issues/296 https://github.com/ReactiveX/RxJava/issues/748

您的问题的解决方案：抓住您的 OutOfMemoryError 但将任何适当的 Exception 子类推入流。

p.s。提示：对于您的情况，请使用 Observable.fromCallable 而不是 Observable.create

使用 OutOfMemoryException 调用订阅者 onError() 时出现 IllegalStateException

IllegalStateException When Calling Subscriber onError() with OutOfMemoryException

java

android

out-of-memory

rx-java