GPUImage recalculateViewGeometry卡UI线程的问题

原因：
更新xocde11.4之后发现GPUImage视频画面渲染特别慢，并且控制台输出如下信息：

Main Thread Checker: UI API called on a background thread: -[UIView bounds]
PID: 7360, TID: 1812926, Thread name: (none), Queue name: com.sunsetlakesoftware.GPUImage.openGLESContextQueue, QoS: 0
Backtrace:

4   KXLive                              0x0000000100e12e60 __39-[GPUImageView recalculateViewGeometry]_block_invoke + 52

5   KXLive                              0x0000000100dec788 runSynchronouslyOnVideoProcessingQueue + 108

6   KXLive                              0x0000000100e12e0c -[GPUImageView recalculateViewGeometry] + 108

7   KXLive                              0x0000000100e13804 __37-[GPUImageView setInputSize:atIndex:]_block_invoke + 312

8   KXLive                              0x0000000100dec788 runSynchronouslyOnVideoProcessingQueue + 108

9   KXLive                              0x0000000100e136ac -[GPUImageView setInputSize:atIndex:] + 136

10  KXLive                              0x0000000100e0ee38 -[GPUImageVideoCamera updateTargetsForVideoCameraUsingCacheTextureAtWidth:height:time:] + 660

11  KXLive                              0x0000000100e0fb48 -[GPUImageVideoCamera processVideoSampleBuffer:] + 2120

12  KXLive                              0x0000000100e106c4 __74-[GPUImageVideoCamera captureOutput:didOutputSampleBuffer:fromConnection:]_block_invoke + 180

13  libdispatch.dylib                   0x0000000105e5d260 _dispatch_call_block_and_release + 24

14  libdispatch.dylib                   0x0000000105e5d220 _dispatch_client_callout + 16

15  libdispatch.dylib                   0x0000000105e6be80 _dispatch_queue_serial_drain + 768

16  libdispatch.dylib                   0x0000000105e60730 _dispatch_queue_invoke + 328

17  libdispatch.dylib                   0x0000000105e6cdd8 _dispatch_root_queue_drain_deferred_wlh + 352

18  libdispatch.dylib                   0x0000000105e73ebc _dispatch_workloop_worker_thread + 676

19  libsystem_pthread.dylib             0x0000000181e6fe70 _pthread_wqthread + 860

20  libsystem_pthread.dylib             0x0000000181e6fb08 start_wqthread + 4

意思是在子线程中UIView对象调用了bounds ，导致视频画面迟迟渲染不出来。
查找发现GPUImageView的视频渲染类的

(void)recalculateViewGeometry;

- (void)layoutSubviews {

    [super layoutSubviews];
self.viewBounds = self.bounds;
// The frame buffer needs to be trashed and re-created when the view size changes.
if (!CGSizeEqualToSize(self.bounds.size, boundsSizeAtFrameBufferEpoch) &&
!CGSizeEqualToSize(self.bounds.size, CGSizeZero)) {
runSynchronouslyOnVideoProcessingQueue(^{

            [self destroyDisplayFramebuffer];

            [self createDisplayFramebuffer];

            [self recalculateViewGeometry];

        });

    }

}

- (void)recalculateViewGeometry;

{
runSynchronouslyOnVideoProcessingQueue(^{

        CGFloat heightScaling, widthScaling;


        CGSize currentViewSize = self.viewBounds.size;

//    CGFloat imageAspectRatio = inputImageSize.width / inputImageSize.height;
//    CGFloat viewAspectRatio = currentViewSize.width / currentViewSize.height;


        CGRect insetRect = AVMakeRectWithAspectRatioInsideRect(inputImageSize, self.viewBounds);