Opencv C++ Raspberry Pi Crashes - c++

Question

Ive been stuck with this problem for a few days and I thought I'd ask for help.
I have written this test code to display my issue
this is my take picture function
cv::Mat takePicture(){
cv::Mat pic;
VideoCapture cam(0);
if(!cam.isOpened()){
std::cout << "Failed to make connection to Cam" << std::endl;
exit(1);
}
cam.set(CV_CAP_PROP_FRAME_WIDTH, 320);
cam.set(CV_CAP_PROP_FRAME_HEIGHT, 240);
cam >> pic;
cvWaitKey(100);
return pic.clone();
}
this is a loop in my main function that will cause a crash
if(test_mode == true){
while(true){
Mat testImg;
char fileName[50];
sprintf(fileName, "testFile%d", threadNo);
testImg = takePicture();
cout << "current pic is " << threadNo << endl;
threadNo++;
testImg.release();
}
}
The program will run fine until image 27 it will then go slower and by image 30 I will get a variety of errors they are
mmap: Cannot allocate memory
munmap: Invalid argument
Unable to stop the stream.: Bad file descriptor
libv4l1: error allocating v4l1 buffers: Cannot allocate memory
HIGHGUI ERROR: V4L: Mapping Memmory from video source error: Invalid argument
HIGHGUI ERROR: V4L: Initial Capture Error: Unable to load initial memory buffers
*** glibc detected *** ./Cam: free(): invalid pointer: 0x0076ab88 ***
Aborted
I keep thinking this must be caused by a leak. Thanks in advance for the help.