CGAL users discussion list

[Bernhard Kornberger <>]

Hello!

I use CGAL 3.9 and my multithreaded code fails occasionally. Now I'd
like to ask if the respective part of CGAL is thread safe? Here is a
code snippet:

***
#define CGAL_HAS_THREADS
typedef CGAL::Exact_predicates_exact_constructions_kernel K;

class ESegment_3 : public K::Segment_3
{
  ...
}

EPoint_3* ESegment_3::splitLowPoint(const K::Line_3& axLin)
{
  if(CGAL::do_intersect(*this,axLin)) // Line 582
  {
  }
}
***

There are 8 std::vector<ESegment*>, and they are treated by 8
separate threads. Each ESegment is unique. Here is a backtrace,
created with gdb:

***

[Switching to Thread 0x7fffe3fff700 (LWP 28117)]
CGAL::Lazy_rep_1<CGAL::Object_cast<CGAL::Point_3<CGAL::Simple_cartesian<CGAL::Interval_nt<false> 
> > >, 
CGAL::Object_cast<CGAL::Point_3<CGAL::Simple_cartesian<CGAL::Gmpq> > >, 
CGAL::Cartesian_converter<CGAL::Simple_cartesian<CGAL::Gmpq>, 
CGAL::Simple_cartesian<CGAL::Interval_nt<false> >, 
CGAL::NT_converter<CGAL::Gmpq, CGAL::Interval_nt<false> > >, 
CGAL::Lazy<CGAL::Object, CGAL::Object, CGAL::Gmpq, 
CGAL::Cartesian_converter<CGAL::Simple_cartesian<CGAL::Gmpq>, 
CGAL::Simple_cartesian<CGAL::Interval_nt<false> >, 
CGAL::NT_converter<CGAL::Gmpq, CGAL::Interval_nt<false> > > > 
>::update_exact (
    this=0x99dcfd0) at /opt/CGAL39_ALL/include/CGAL/Lazy.h:328
328         this->et = new ET(ec()(CGAL::exact(l1_)));
(gdb) backtrace
#0 
CGAL::Lazy_rep_1<CGAL::Object_cast<CGAL::Point_3<CGAL::Simple_cartesian<CGAL::Interval_nt<false> 
> > >, 
CGAL::Object_cast<CGAL::Point_3<CGAL::Simple_cartesian<CGAL::Gmpq> > >, 
CGAL::Cartesian_converter<CGAL::Simple_cartesian<CGAL::Gmpq>, 
CGAL::Simple_cartesian<CGAL::Interval_nt<false> >, 
CGAL::NT_converter<CGAL::Gmpq, CGAL::Interval_nt<false> > >, 
CGAL::Lazy<CGAL::Object, CGAL::Object, CGAL::Gmpq, 
CGAL::Cartesian_converter<CGAL::Simple_cartesian<CGAL::Gmpq>, 
CGAL::Simple_cartesian<CGAL::Interval_nt<false> >, 
CGAL::NT_converter<CGAL::Gmpq, CGAL::Interval_nt<false> > > > 
>::update_exact (
    this=0x99dcfd0) at /opt/CGAL39_ALL/include/CGAL/Lazy.h:328
#1  0x00000000004ae48a in exact (this=0x99dd350) at 
/opt/CGAL39_ALL/include/CGAL/Lazy.h:239
#2  exact (this=0x99dd350) at /opt/CGAL39_ALL/include/CGAL/Lazy.h:1148
#3  exact<CGAL::Point_3<CGAL::Simple_cartesian<CGAL::Interval_nt<false> 
> >, CGAL::Point_3<CGAL::Simple_cartesian<CGAL::Gmpq> >, CGAL::Gmpq, 
CGAL::Cartesian_converter<CGAL::Simple_cartesian<CGAL::Gmpq>, 
CGAL::Simple_cartesian<CGAL::Interval_nt<false> > > > (this=0x99dd350) 
at /opt/CGAL39_ALL/include/CGAL/Lazy.h:71
#4 
CGAL::Lazy_rep_1<CGAL::CartesianKernelFunctors::Compute_z_3<CGAL::Simple_cartesian<CGAL::Interval_nt<false> 
> >, 
CGAL::CartesianKernelFunctors::Compute_z_3<CGAL::Simple_cartesian<CGAL::Gmpq> 
>, CGAL::To_interval<CGAL::Gmpq>, CGAL::Point_3<CGAL::Epeck> 
>::update_exact (this=0x99dd350) at /opt/CGAL39_ALL/include/CGAL/Lazy.h:328
#5  0x00000000004d862a in exact (this=0x99dddd0) at 
/opt/CGAL39_ALL/include/CGAL/Lazy.h:239
#6  exact (this=0x99dddd0) at /opt/CGAL39_ALL/include/CGAL/Lazy.h:1148
#7  exact<CGAL::Interval_nt<false>, CGAL::Gmpq, 
CGAL::Lazy_exact_nt<CGAL::Gmpq>, CGAL::To_interval<CGAL::Gmpq> > 
(this=0x99dddd0) at /opt/CGAL39_ALL/include/CGAL/Lazy.h:71
#8 
CGAL::Lazy_rep_4<CGAL::CartesianKernelFunctors::Construct_point_3<CGAL::Simple_cartesian<CGAL::Interval_nt<false> 
> >, 
CGAL::CartesianKernelFunctors::Construct_point_3<CGAL::Simple_cartesian<CGAL::Gmpq> 
>, CGAL::Cartesian_converter<CGAL::Simple_cartesian<CGAL::Gmpq>, 
CGAL::Simple_cartesian<CGAL::Interval_nt<false> >, 
CGAL::NT_converter<CGAL::Gmpq, CGAL::Interval_nt<false> > >, 
CGAL::Return_base_tag, CGAL::Lazy_exact_nt<CGAL::Gmpq>, 
CGAL::Lazy_exact_nt<CGAL::Gmpq>, CGAL::Lazy_exact_nt<CGAL::Gmpq> 
>::update_exact (this=0x99dddd0) at /opt/CGAL39_ALL/include/CGAL/Lazy.h:488
#9  0x0000000000509cea in exact (this=0x99de380) at 
/opt/CGAL39_ALL/include/CGAL/Lazy.h:239
#10 exact (this=0x99de380) at /opt/CGAL39_ALL/include/CGAL/Lazy.h:1148
#11 exact<CGAL::Point_3<CGAL::Simple_cartesian<CGAL::Interval_nt<false> 
> >, CGAL::Point_3<CGAL::Simple_cartesian<CGAL::Gmpq> >, CGAL::Gmpq, 
CGAL::Cartesian_converter<CGAL::Simple_cartesian<CGAL::Gmpq>, 
CGAL::Simple_cartesian<CGAL::Interval_nt<false> > > > (this=0x99de380) 
at /opt/CGAL39_ALL/include/CGAL/Lazy.h:71
#12 
CGAL::Lazy_rep_3<CGAL::CommonKernelFunctors::Construct_segment_3<CGAL::Simple_cartesian<CGAL::Interval_nt<false> 
> >, 
CGAL::CommonKernelFunctors::Construct_segment_3<CGAL::Simple_cartesian<CGAL::Gmpq> 
>, CGAL::Cartesian_converter<CGAL::Simple_cartesian<CGAL::Gmpq>, 
CGAL::Simple_cartesian<CGAL::Interval_nt<false> >, 
CGAL::NT_converter<CGAL::Gmpq, CGAL::Interval_nt<false> > >, 
CGAL::Return_base_tag, CGAL::Point_3<CGAL::Epeck>, 
CGAL::Point_3<CGAL::Epeck> >::update_exact (this=0x99de380) at 
/opt/CGAL39_ALL/include/CGAL/Lazy.h:428
#13 0x00000000005133e1 in exact (this=<value optimized out>, a1=..., 
a2=<value optimized out>) at /opt/CGAL39_ALL/include/CGAL/Lazy.h:239
#14 exact (this=<value optimized out>, a1=..., a2=<value optimized out>) 
at /opt/CGAL39_ALL/include/CGAL/Lazy.h:1148
#15 operator()<CGAL::Segment_3<CGAL::Epeck> > (this=<value optimized 
out>, a1=..., a2=<value optimized out>) at 
/opt/CGAL39_ALL/include/CGAL/Lazy.h:869
#16 
CGAL::Filtered_predicate<CGAL::CommonKernelFunctors::Do_intersect_3<CGAL::Simple_cartesian<CGAL::Gmpq> 
>, 
CGAL::CommonKernelFunctors::Do_intersect_3<CGAL::Simple_cartesian<CGAL::Interval_nt<false> 
> >, CGAL::Exact_converter<CGAL::Epeck, 
CGAL::Simple_cartesian<CGAL::Gmpq> >, 
CGAL::Approx_converter<CGAL::Epeck, 
CGAL::Simple_cartesian<CGAL::Interval_nt<false> > >, 
true>::operator()<CGAL::Line_3<CGAL::Epeck>, 
CGAL::Segment_3<CGAL::Epeck> > (this=<value optimized out>, a1=..., 
a2=<value optimized out>) at 
/opt/CGAL39_ALL/include/CGAL/Filtered_predicate.h:217
#17 0x0000000000505858 in do_intersect<CGAL::Epeck> (this=0x994d7b0, 
pData=..., axLin=...) at 
/opt/CGAL39_ALL/include/CGAL/Intersections_3/intersection_3_1_impl.h:1596
#18 do_intersect<CGAL::Epeck> (this=0x994d7b0, pData=..., axLin=...) at 
/opt/CGAL39_ALL/include/CGAL/intersection_3_1.h:329
#19 GEOM_RCT::ESegment_3::splitLowPoint (this=0x994d7b0, pData=..., 
axLin=...) at /home/bernd/openSource/windev64/rctLib/ESegment_3.cpp:582


(gdb) info threads
  9 Thread 0x7fffe37fe700 (LWP 28118)  __mcount_internal 
(frompc=5153075, selfpc=4838414) at mcount.c:72
* 8 Thread 0x7fffe3fff700 (LWP 28117) 
CGAL::Lazy_rep_1<CGAL::Object_cast<CGAL::Point_3<CGAL::Simple_cartesian<CGAL::Interval_nt<false> 
> > >, 
CGAL::Object_cast<CGAL::Point_3<CGAL::Simple_cartesian<CGAL::Gmpq> > >, 
CGAL::Cartesian_converter<CGAL::Simple_cartesian<CGAL::Gmpq>, 
CGAL::Simple_cartesian<CGAL::Interval_nt<false> >, 
CGAL::NT_converter<CGAL::Gmpq, CGAL::Interval_nt<false> > >, 
CGAL::Lazy<CGAL::Object, CGAL::Object, CGAL::Gmpq, 
CGAL::Cartesian_converter<CGAL::Simple_cartesian<CGAL::Gmpq>, 
CGAL::Simple_cartesian<CGAL::Interval_nt<false> >, 
CGAL::NT_converter<CGAL::Gmpq, CGAL::Interval_nt<false> > > > 
>::update_exact (this=0x99dcfd0) at /opt/CGAL39_ALL/include/CGAL/Lazy.h:328
  6 Thread 0x7ffff13e1700 (LWP 28115)  0x00007ffff773b1b6 in 
__gmpz_divexact () from /usr/lib/libgmp.so.3
  5 Thread 0x7ffff1be2700 (LWP 28114)  0x00007ffff774d1a0 in 
__gmpn_mul_1 () from /usr/lib/libgmp.so.3
  4 Thread 0x7ffff23e3700 (LWP 28113)  __strlen_sse42 () at 
../sysdeps/x86_64/multiarch/strlen-sse4.S:33
  3 Thread 0x7ffff2be4700 (LWP 28112)  0x00007ffff775a2f5 in 
__gmpn_gcd_1 () from /usr/lib/libgmp.so.3
  2 Thread 0x7ffff33e5700 (LWP 28111)  fesetround (round=0) at 
../sysdeps/x86_64/fpu/fesetround.c:41
  1 Thread 0x7ffff7fbd740 (LWP 28107)  pthread_cond_wait@@GLIBC_2.3.2 
() at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
***

I have tried to create a minimal example with randomly created
segments, but that worked. Any hints are appreciated, thank you!

best regards