Memory fragmentation with posix_memalign

fragment.cpp

#include <thread>
#include <utility>
#include <vector>
#include <stdlib.h>
#include <string.h>
#include <iostream>
#include <malloc.h>

using namespace std;

const size_t sz = 3 * 1000 * 1000;
inline void delay() { std::this_thread::sleep_for(std::chrono::milliseconds(10)); }

// switch between raw malloc calls and OpenCV
#if 1

// swtich between posix_memalign calls and malloc
#if 1
#define INIT(a) 0
#define POSIX_MEMALIGN(a, b, c) posix_memalign((a), (b), (c))
#else
#define INIT(a) (char*)malloc((a))
#define POSIX_MEMALIGN(a, b, c)
#endif

int main()
{
    char * buf = INIT(sz);
    POSIX_MEMALIGN((void**)&buf, 64, sz);
    memset(buf, 0, sz);
    std::vector<std::string> strings;
    for (size_t i = 0; i < 8000; ++i)
    {
        if (i % 100 == 0) cout << "===== Iter " << i << endl;
        char * buf2 = INIT(sz);
        POSIX_MEMALIGN((void**)&buf2, 64, sz);
        if (i % 100 == 0) cout << (void*)buf << " ; " << (void*)buf2 << endl;
        memset(buf2, 0, sz);
        free(buf);
        buf = buf2;
        strings.push_back(std::string("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"));
        delay();
        if (i % 100 == 0) malloc_stats();
    }
    free(buf);
}

#else

#include <opencv2/core/mat.hpp>

int main()
{
    cv::Size size(sz, 1);
    cv::Mat tmp(size, CV_8UC1, cv::Scalar(0, 0, 0));
    std::vector<std::string> strings;
    for (size_t i = 0; i < 2000; ++i)
    {
        if (i % 100 == 0) cout << "===== Iter " << i << endl;
        cv::Mat tmp2(size, CV_8UC1, cv::Scalar(0, 0, 0));
        if (i % 100 == 0) cout << (void*)tmp.data << " ; " << (void*)tmp2.data << endl;
        tmp = tmp2;
        strings.push_back(std::string("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"));
        delay();
        if (i % 100 == 0) malloc_stats();
    }
}

#endif