【记录一个问题】opencv中使用UMat类，在析构的时候出现refcount == 0的断言错误

发生coredump时的错误信息如下：

terminate called after throwing an instance of 'cv::Exception'
what(): OpenCV(4.1.0-dev) /home/admin/opencv/opencv-master/modules/core/src/matrix.cpp:169: error: (-215:Assertion failed) u->refcount == 0 in function 'deallocate'

以下写法导致这种断言错误：

cv::resize(u_input_gray, u_input_gray, cv::Size(0, 0), 0.5, 0.5,

      cv::INTER_AREA);

 

 重新编译了debug版本，具体调用堆栈如下：

#7  0x00007ffff6f233d7 in _Unwind_Resume (exc=0x128f3e0) at ../../../libgcc/unwind.inc:230
#8  0x00000000004589b9 in cv::StdMatAllocator::deallocate (this=0x1209b90, u=0x1269640)
    at /home/admin/opencv/opencv-master/modules/core/src/matrix.cpp:169
#9  0x00000000004fcc17 in cv::UMat::deallocate (this=0x7fffffffd990) at /home/admin/opencv/opencv-master/modules/core/src/umatrix.cpp:490
#10 0x0000000000461893 in cv::UMat::release (this=0x7fffffffd990)
    at /home/admin/opencv/opencv-master/modules/core/include/opencv2/core/mat.inl.hpp:3777
#11 0x00000000004fcb9c in cv::UMat::~UMat (this=0x7fffffffd990, __in_chrg=<optimized out>)
    at /home/admin/opencv/opencv-master/modules/core/src/umatrix.cpp:481

p u->refcount
$1 = 6

析构的时候，发现有6个引用，所以崩溃……
===================================

解决办法如下：
不要使用 getMat() 或者 getUMat() 方法

而使用 mat.copyTo(umat) 或者 umat.copyTo(mat)

通过拷贝来避免UMat和mat的关联