无法在 Ubuntu 中执行 pthread 程序

Question

我编写了一个同时使用 openCV 和 Pthreads 的 C++ 程序。

代码如下，

#include <opencv2/imgcodecs.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc.hpp>
#include <iostream>
#include <pthread.h>
#include <unistd.h>
#include <stdio.h>

using namespace cv;
using namespace std;

int lowThreshold=0;
int const max_lowThreshold = 100;
int kernel_size = 3;
int ratio = 3;

Mat img;
Mat display;
Mat temp;

void CannyThreshold()
{
    cvtColor(img, display, COLOR_RGB2GRAY);

    GaussianBlur(display, display, Size(1, 1), 1,1);

    Canny(display,display,lowThreshold,3);

    imshow("Canny",display);
}

void Hough()
{
    Mat dip = temp.clone(); 
    
    medianBlur(temp,temp,9);
    Canny(temp,display,50,200);

    vector<Vec2f> lines; // will hold the results of the detection
    HoughLines(display, lines, 1, CV_PI/180, 150, 30, 0 ); // runs the actual detection    

    for( size_t i = 0; i < lines.size(); i++ )
    {
        float rho = lines[i][0], theta = lines[i][1];
        Point pt1, pt2;
        double a = cos(theta), b = sin(theta);
        double x0 = a*rho, y0 = b*rho;
        pt1.x = cvRound(x0 + 1000*(-b));
        pt1.y = cvRound(y0 + 1000*(a));
        pt2.x = cvRound(x0 - 1000*(-b));
        pt2.y = cvRound(y0 - 1000*(a));
        line(dip, pt1, pt2, Scalar(0,0,255), 3, LINE_AA);
    }

    printf("Lines = %ld\n",lines.size());

    imshow("Hough",dip);

}

void * transform(void * param)
{
    VideoCapture cap(0);

    namedWindow("Canny");
    createTrackbar("Min Threshold: ","Canny",&lowThreshold,max_lowThreshold);

    while(1)
    {
        cap.read(img);

        temp = img;

        CannyThreshold();
        Hough();

        waitKey(1);
    }

    cap.release();
}

int main()
{

    pthread_t transformThread;
    pthread_attr_t transformThread_attr;
    struct sched_param rt_param;

    pthread_attr_init(&transformThread_attr);
    pthread_attr_setinheritsched(&transformThread_attr, PTHREAD_EXPLICIT_SCHED);
    pthread_attr_setschedpolicy(&transformThread_attr, SCHED_FIFO);

    int rt_max_prio = sched_get_priority_max(SCHED_FIFO);
    int rt_min_prio = sched_get_priority_min(SCHED_FIFO);

    rt_min_prio += 1; //To avoid compiler error for unused variable

    rt_param.sched_priority = rt_max_prio - 10;
    pthread_attr_setschedparam(&transformThread_attr, &rt_param);

    int ret = pthread_create(&transformThread,&transformThread_attr,transform,NULL);

    if(ret !=0)
    {
        perror("pthread_create()");
    }

    void * res;

    pthread_join(transformThread,&res);

    return 0;
}

我编写的make文件如下，

    CC = g++
CFLAGS = -g -Wall
SRCS = main.cpp
PROG = main
LIBS = -lrt
CPPLIBS= -L/usr/lib -lopencv_core -lopencv_flann -lopencv_video -lpthread -pthread

OPENCV = `pkg-config opencv --cflags --libs`

$(PROG):$(SRCS)
    $(CC) $(CFLAGS) -o $(PROG) $(SRCS) `pkg-config --libs opencv4` $(CPPLIBS)

clean: 
    rm -rf main

当我执行程序时（不是当我编译它时），我收到以下错误。

pthread_create()：没有这样的文件或目录

如何解决此问题？对此有何建议？