Simultaneous CGAL calculations in multiple threads - c++

Question

I'm trying to run multiple geometric calculations with CGAL simultaneously in multiple threads. All threads are 100% "isolated" from each other. Nevertheless the app crashes with an access violation:
http://s8.postimg.org/52u9qphdx/error.png
I've build a small example app to reproduce the error:
main.cpp
#include <fstream>
#include "windows.h"
#include "cTestClass.h"
int main ( int argc, char *argv[] ){
cTestClass *eval0 = new cTestClass("d://.partion_2.stl", 0);
cTestClass *eval1 = new cTestClass("d://.partion_2.stl", 1);
eval0->start_eval();
eval1->start_eval();
while (!eval0->eval_finished())
{
Sleep(200);
}
while (!eval1->eval_finished())
{
Sleep(200);
}
return EXIT_SUCCESS;
}
cTestClass.h
#ifndef CTEST_CLASS_H
#define CTEST_CLASS_H
#include <atomic>
#include <thread>
class cTestClass
{
private:
std::atomic<bool> flag_eval_finished;
std::thread eval_thread;
std::string stl_file_name;
unsigned int thread_index;
cTestClass(){ }
void evaluate_partition();
public:
cTestClass(std::string argStlFile, unsigned int argThread_index);
void start_eval();
bool eval_finished();
};
#endif
cTestClass.cpp
#include "cTestClass.h"
#include <CGAL/Exact_predicates_exact_constructions_kernel.h>
#include <CGAL/Polyhedron_3.h>
#include <CGAL/Nef_polyhedron_3.h>
#include <CGAL/polygon_soup_to_polyhedron_3.h>
#include <CGAL/IO/Polyhedron_builder_from_STL.h>
#include <iostream>
#include <fstream>
//typedef CGAL::Cartesian<double> Kernel;
typedef CGAL::Exact_predicates_exact_constructions_kernel Kernel;
typedef CGAL::Polyhedron_3<Kernel> Polyhedron_3;
typedef CGAL::Nef_polyhedron_3<Kernel> Nef_polyhedron_3;
typedef CGAL::Point_3<Kernel> Point_3;
//typedef Polyhedron::Point_iterator Point_iterator;
typedef Polyhedron_3::Vertex_iterator Vertex_iterator;
typedef Polyhedron_3::Facet_iterator Facet_iterator;
typedef Polyhedron_3::Halfedge_around_facet_circulator Halfedge_facet_circulator;
typedef Nef_polyhedron_3::Volume_const_iterator Volume_const_iterator;
typedef Kernel::Iso_cuboid_3 Iso_cuboid;
//constructor
cTestClass::cTestClass(std::string argStlFile, unsigned int argThread_index)
{
thread_index = argThread_index;
stl_file_name = argStlFile;
flag_eval_finished = false;
}
//===========================================================================================
// public member functions
void cTestClass::start_eval()
{
std::cout << "Thread " << thread_index << ": start" << std::endl;
eval_thread = std::thread(&cTestClass::evaluate_partition, this);
}
bool cTestClass::eval_finished()
{
return flag_eval_finished;
}
//===========================================================================================
//private member functions
void cTestClass::evaluate_partition()
{
//read stl file and create cgal polyhedron
Polyhedron_3 poly_Partition;
std::ifstream stl_file(stl_file_name.c_str(), std::ifstream::in);
std::vector<CGAL::cpp11::array<double, 3> > points;
std::vector<CGAL::cpp11::array<int, 3> > triangles;
CGAL::read_STL(stl_file, points, triangles);
stl_file.close();
//create polyhedron
CGAL::polygon_soup_to_polyhedron_3(poly_Partition, points, triangles);
//convert polyhedron to nef_poly representation
std::cout << "Thread " << thread_index << ": " <<"Converting partition polyhedron to Nef representation" << std::endl;
Nef_polyhedron_3 nefpoly_Partition(poly_Partition);
flag_eval_finished = true;
}
Anyone got an idea what causes this crash?
Best regards
Monchi