C++ windows 多线程 互斥锁
#include <opencv2/core/version.hpp>#include <opencv2/calib3d/calib3d.hpp>
#include <opencv2/opencv.hpp>
using namespace System::Runtime::InteropServices;
using namespace System::IO;
using namespace System::Data;
using namespace System::Drawing;
using namespace System::Drawing::Imaging;
using namespace System::Runtime::Serialization::Formatters::Binary;
using namespace System::Windows::Forms;
using namespace System::Threading;
using namespace FRS;
using namespace FRS::Util;
using namespace DataAngine;
HANDLE hMutex = CreateMutex(NULL,FALSE,NULL);
cv::VideoCapture *cap;
void Show(){
while (true){
cv::Mat frame;
WaitForSingleObject(hMutex, INFINITE);
cap>>frame;
ReleaseMutex(hMutex);
imshow("video", frame);
cv::waitKey(1000 / cap->get(CV_CAP_PROP_FPS));
}
}
int main()
{
FeatureData ^fa = gcnew FeatureData();
//cap.open(0);
cap = new cv::VideoCapture();
cap->open("rtsp://admin:admin12345@172.18.132.234:554");
if (!cap->isOpened())
{
std::cout << "open rtsp error" << std::endl;
return 0;
}
Thread ^showThread = gcnew Thread(gcnew ThreadStart(Show));
showThread->Start();
bool stop = true;
while (stop)
{
cv::Mat frame;
WaitForSingleObject(hMutex, INFINITE);
cap>>frame;
ReleaseMutex(hMutex);
if (frame.empty()) continue;
System::GC::Collect();
Thread::Sleep(100);
}
}
本代码为人脸识别视频处理代码，包含两个线程，其中Show线程为opencv读取rtsp流，主线程代码自填。其中GC::Collect()为程序垃圾回收。
代码本为单线程，书写中发现VideoCapture读取视频流时存在缓存，并有缓存上限，单纯进行主线程视频处理时会因为处理时间较长发生缓存溢出问题，所以增设多线程Show()读取消耗VideoCapture缓存。
增设Show()线程时发现存在两线程同时读取缓存现象，添加互斥锁hMutex ，代码中包含互斥锁的句柄初始化以及加锁解锁代码。 看不懂啊！ 谢谢分享
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