I am getting segfault with the following simple code:
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include <iostream>
#include <thread>
#include <unistd.h>
void run() {
sleep(1); // see below
cv::Mat source(10, 10, CV_32FC1, -1);
cv::Mat result(10, 10, CV_32FC1);
cv::Mat trX(result.rows, result.cols, CV_32FC1, 5);
cv::Mat trY(result.rows, result.cols, CV_32FC1, 5);
cv::remap(source, result, trX, trY, cv::INTER_LINEAR, cv::BORDER_TRANSPARENT);
std::cout << "done" << std::endl;
}
int main(int argc, char* argv[]) {
std::thread t1(run);
t1.join();
std::thread t2(run);
t2.join();
return 0;
}
If I call run() twice directly from main(), without using threads at all, it works well. If I swap t1.join(); and std::thread t2(run); (that is, start the second thread before the first finishes; this is where sleep becomes important), it also runs well.
Moreover, if I change main to
int main(int argc, char* argv[]) {
std::thread t1(run);
std::thread t2(run);
t1.join();
t2.join();
std::thread t3(run);
t3.join();
return 0;
}
it segfaults in the third thread, but (strangely) not always: roughly one run of 2-3 passes successfully. However, I was not able to get a successfull run for the program with two threads above.
It seems that particular values in source, trX and trY are not important.
The big program that I was working on was running properly in December, after which I did not have time to work on it, but have updated the system several times. Now the big program fails with exactly the same segfault, so I think it should be something with newer versions of opencv and/or g++ and/or libstdc++.
Is it some problem with my system or my code? Or is it some known problem? Or where should I better report it?
I'm running up-to-date Ubuntu 16.10, with g++ 6.2.0 (I've also tried 4.9 with the same result). The specific versions of packages that may be of interest are:
$ dpkg-query -W -f='${binary:Package}\t${Version}\n' | grep -E '(g\+\+|c\+\+|opencv)'
g++ 4:6.1.1-1ubuntu2
g++-4.9 4.9.4-2ubuntu1
g++-5 5.4.1-2ubuntu2
g++-6 6.2.0-5ubuntu12
lib32stdc++6 6.2.0-5ubuntu12
libflac++6v5:amd64 1.3.1-4
libopencv-calib3d2.4v5:amd64 2.4.9.1+dfsg-2.1
libopencv-contrib2.4v5:amd64 2.4.9.1+dfsg-2.1
libopencv-core-dev:amd64 2.4.9.1+dfsg-2.1
libopencv-core2.4v5:amd64 2.4.9.1+dfsg-2.1
libopencv-features2d2.4v5:amd64 2.4.9.1+dfsg-2.1
libopencv-flann2.4v5:amd64 2.4.9.1+dfsg-2.1
libopencv-highgui-dev:amd64 2.4.9.1+dfsg-2.1
libopencv-highgui2.4-deb0:amd64 2.4.9.1+dfsg-2.1
libopencv-imgproc-dev:amd64 2.4.9.1+dfsg-2.1
libopencv-imgproc2.4v5:amd64 2.4.9.1+dfsg-2.1
libopencv-legacy2.4v5:amd64 2.4.9.1+dfsg-2.1
libopencv-ml2.4v5:amd64 2.4.9.1+dfsg-2.1
libopencv-objdetect2.4v5:amd64 2.4.9.1+dfsg-2.1
libopencv-video2.4v5:amd64 2.4.9.1+dfsg-2.1
libsigc++-2.0-0v5:amd64 2.8.0-2
libstdc++-4.9-dev:amd64 4.9.4-2ubuntu1
libstdc++-5-dev:amd64 5.4.1-2ubuntu2
libstdc++-6-dev:amd64 6.2.0-5ubuntu12
libstdc++6:amd64 6.2.0-5ubuntu12
libstdc++6:i386 6.2.0-5ubuntu12
I use the following command to build the code:
g++ --std=c++14 test.cpp -lpthread -lopencv_highgui -lopencv_core -lopencv_imgproc -o test
Valgrind outputs:
==18499== Thread 2:
==18499== Invalid read of size 8
==18499== at 0x690F0BA: ??? (in /usr/lib/x86_64-linux-gnu/libtbb.so.2)
==18499== by 0x690F18A: ??? (in /usr/lib/x86_64-linux-gnu/libtbb.so.2)
==18499== by 0x6910CE7: ??? (in /usr/lib/x86_64-linux-gnu/libtbb.so.2)
==18499== by 0x690F691: ??? (in /usr/lib/x86_64-linux-gnu/libtbb.so.2)
==18499== by 0x690A01F: ??? (in /usr/lib/x86_64-linux-gnu/libtbb.so.2)
==18499== by 0x6908164: tbb::internal::allocate_root_with_context_proxy::allocate(unsigned long) const (in /usr/lib/x86_64-linux-gnu/libtbb.so.2)
==18499== by 0x51D9E21: cv::parallel_for_(cv::Range const&, cv::ParallelLoopBody const&, double) (in /usr/lib/x86_64-linux-gnu/libopencv_core.so.2.4.9)
==18499== by 0x55AE8A1: cv::remap(cv::_InputArray const&, cv::_OutputArray const&, cv::_InputArray const&, cv::_InputArray const&, int, int, cv::Scalar_<double> const&) (in /usr/lib/x86_64-linux-gnu/libopencv_imgproc.so.2.4.9)
==18499== by 0x1094AC: run() (in /home/petr/osm/draw/test/test)
==18499== by 0x10A360: void std::_Bind_simple<void (*())()>::_M_invoke<>(std::_Index_tuple<>) (in /home/petr/osm/draw/test/test)
==18499== by 0x10A2ED: std::_Bind_simple<void (*())()>::operator()() (in /home/petr/osm/draw/test/test)
==18499== by 0x10A2BD: std::thread::_State_impl<std::_Bind_simple<void (*())()> >::_M_run() (in /home/petr/osm/draw/test/test)
==18499== Address 0xfffffffffffffff7 is not stack'd, malloc'd or (recently) free'd
