Segfault while testing intersection with geospheres

Question

I use the GEOS C API to control geometry in a parallel simulator: I need objects to stay inside a restricted area. To this end, when my object takes a step, I check to see if the lineenvironment boundary ( environment_manager_->get_border()which returns const GEOSPreparedGeometry*) intersects between its previous and current position .

The code works in parallel with several OpenMP threads. I initialized GEOS before starting modeling through

initGEOS_r(notice, log_and_exit);
context_handler_ = GEOS_init_r();

therefore, I have only one handler for all threads. When running a simulation with multiple threads, the code crashes inside env_intersectwith segfault, unless I wrap it GEOSPreparedIntersects_rin a critical section.

bool SpaceManager::env_intersect(const GEOSGeometry * line) const
{
    bool intersect;
    // #pragma omp critical // adding prevents segfault
    // {
        intersect = GEOSPreparedIntersects_r(
            context_handler_, environment_manager_->get_border(), line);
    // }
    return intersect;
}

- , ? GEOS, - OpenMP? , environment_manager_ unique_ptr? ?

---

segfault :

Thread 19 "python" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffd63da700 (LWP 4374)]
0x00007ffff78816b2 in tcache_get () from /usr/lib/libc.so.6
(gdb) bt
#0  0x00007ffff78816b2 in tcache_get () at /usr/lib/libc.so.6
#1  0x00007ffff5dbf0a9 in operator new(unsigned long) (sz=sz@entry=32)
    at /build/gcc-multilib/src/gcc/libstdc++-v3/libsupc++/new_op.cc:50
#2  0x00007fffc8468273 in geos::geom::LineString::computeEnvelopeInternal() const (this=0x555555f10170) at LineString.cpp:278
#3  0x00007fffc845b95f in geos::geom::Geometry::getEnvelopeInternal() const (this=0x555555f10180) at Geometry.cpp:276
#4  0x00007fffc84612ad in geos::geom::GeometryCollection::computeEnvelopeInternal() const (this=0x555555f15980) at GeometryCollection.cpp:257
#5  0x00007fffc845b95f in geos::geom::Geometry::getEnvelopeInternal() const (this=0x555555f15998) at Geometry.cpp:276
#6  0x00007ffff53cea66 in geos::geom::prep::BasicPreparedGeometry::envelopesIntersect(geos::geom::Geometry const*) const () at /usr/lib/libgeos-3.6.2.so
#7  0x00007ffff53cef82 in geos::geom::prep::PreparedLineString::intersects(geos::geom::Geometry const*) const () at /usr/lib/libgeos-3.6.2.so
#8  0x00007ffff5907380 in GEOSPreparedIntersects_r ()
    at /usr/lib/libgeos_c.so.1
#9  0x00007ffff61d7938 in growth::SpaceManager::env_intersect(GEOSGeom_t const*) const (this=0x555555fb3b78, line=0x7fff7c045c20)

---

[EDIT], const GEOSPreparedGeometry* OMP, segfault critical. :

intersect = GEOSPreparedIntersects_r(
        context_handler_, environment_manager_->get_border(omp_id), line);

environment_manager_->get_border(omp_id) const GEOSPreparedGeometry*. , , . , ...

Answer 1

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