segmentation fault if too many variables and constraints.

[Tahiti410]

Description

Segmentation fault if too many(about 140k) constraints and states.

I guess it's related to the resources release(recursive) in descrutors.

Steps to reproduce

1. check/set the stack size of your machine by ulimit -s 8192
2. Replace the code in example/LocalizationExample.cpp by code in Additional information.
3. cd build
4. build an run the demo program by make -j8 LocalizationExample && ./example/LocalizationExample

Expected behavior

Segmentation fault (core dumped)

Environment

Masterdevelop branch of gtsam
Linux version 5.4.0-52-generic (buildd@xxx-amd64-022) (gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)) #57~18.04.1-Ubuntu SMP Thu Oct 15 14:04:49 UTC 2020

ulimit -s output 8192

Additional information

#include <gtsam/geometry/Pose2.h>
#include <gtsam/inference/Key.h>
#include <gtsam/nonlinear/LevenbergMarquardtOptimizer.h>
#include <gtsam/nonlinear/NonlinearFactor.h>
#include <gtsam/nonlinear/NonlinearFactorGraph.h>
#include <gtsam/nonlinear/Values.h>
#include <gtsam/slam/BetweenFactor.h>

using namespace std;
using namespace gtsam;

class UnaryFactor : public NoiseModelFactor1<Pose2> {
  double mx_, my_;

 public:
  typedef boost::shared_ptr<UnaryFactor> shared_ptr;
  UnaryFactor(Key j, double x, double y, const SharedNoiseModel& model)
      : NoiseModelFactor1<Pose2>(model, j), mx_(x), my_(y) {}

  ~UnaryFactor() override {}
  Vector evaluateError(const Pose2& q, boost::optional<Matrix&> H = boost::none) const override {
    const Rot2& R = q.rotation();
    if (H) (*H) = (gtsam::Matrix(2, 3) << R.c(), -R.s(), 0.0, R.s(), R.c(), 0.0).finished();
    return (Vector(2) << q.x() - mx_, q.y() - my_).finished();
  }
  gtsam::NonlinearFactor::shared_ptr clone() const override {
    return boost::static_pointer_cast<gtsam::NonlinearFactor>(
        gtsam::NonlinearFactor::shared_ptr(new UnaryFactor(*this)));
  }
};

int main(int argc, char** argv) {
  NonlinearFactorGraph graph;
  const auto odom_noise = noiseModel::Diagonal::Sigmas(Vector3(0.2, 0.2, 0.1));
  const auto unary_noise = noiseModel::Diagonal::Sigmas(Vector2(0.1, 0.1));
  Values initial_state;

  const int num_state = 135250;
  graph.emplace_shared<UnaryFactor>(0, 0.0, 0.0, unary_noise);
  graph.emplace_shared<UnaryFactor>(num_state - 1, num_state * 1.0, 0.0, unary_noise);
  for (int i = 0; i < num_state; ++i) {
    initial_state.insert(i, Pose2(i, 0.0, 0.0));
  }
  for (int i = 0; i < num_state - 1; ++i) {
    graph.emplace_shared<BetweenFactor<Pose2> >(i, i + 1, Pose2(1.0, 0.0, 0.0), odom_noise);
  }

  LevenbergMarquardtOptimizer optimizer(graph, initial_state);
  std::cout << "Start to optimize." << std::endl;
  const Values result = optimizer.optimize();
  std::cout << "Optimization finished." << std::endl;
  if (result.exists(num_state - 1)) {
    const Pose2 end_pose = result.at<Pose2>(num_state - 1);
    end_pose.print("End pose2:\n");
  }

  return 0;
}

[Tahiti410]

cc @ProfFan thanks~

[ProfFan]

Hi @Tahiti410 , by "Master code of gtsam" do you mean master or develop? develop is the latest branch.

[Tahiti410]

Hi @Tahiti410 , by "Master code of gtsam" do you mean master or develop? develop is the latest branch.

Sorry, it's develop branch

[ProfFan]

I think this is also related to #809. A race condition caused the stack to overflow. @acxz @varunagrawal We should probably revert #800 for now to unbreak develop and find the ultimate cause.

[ProfFan]

In the meantime, @Tahiti410 could you try the fix mentioned in #809 ?

[ProfFan]

Though this can be an issue of the multifrontal solver in the presence of large chains like the one in this reproducer. I am not sure.

EDIT: This IS the cause.

[ProfFan]

Maybe this:

      void processNodeRecursively(const boost::shared_ptr<NODE>& node, DATA& myData)
        {
          for(const boost::shared_ptr<NODE>& child: node->children)
          {
            DATA childData = visitorPre(child, myData);
            processNodeRecursively(child, childData);
          }

          // Run the post-order visitor
          (void) visitorPost(node, myData);
        }
      };

should be rewritten to not use recursion.

[ProfFan]

Ok, by using ulimit -s 65535 I don't get crashes anymore. So this is not a TBB issue. @Tahiti410

But still it would be great if we can do this without needing to change ulimit.

[ProfFan]

Closing as this is resolved.