Add a regression test for a cyclic component reference

Stores a painted cube, points its component back at the object that holds it and
expects the load to fail. Without the bound the test does not finish: the work
list grows until the process is killed.

src/libslic3r/CutSurface.cpp

@@ -809,20 +809,13 @@ void priv::set_skip_for_out_of_aoi(std::vector<bool>          &skip_indicies,
     }); // END parallel for
 
     // inspect all triangles, when it is out of bounding box
-    // NOTE: std::vector<bool> is bit packed, thus setting its items from multiple threads is a
-    // read-modify-write race on the shared words and silently loses flags. Collect the flags into
-    // a byte per triangle, where the chunks do not share memory, and merge them afterwards.
-    std::vector<unsigned char> skip_triangle(its.indices.size(), 0);
     tbb::parallel_for(tbb::blocked_range<size_t>(0, its.indices.size()),
-    [&its, &is_on_sides, &skip_triangle](const tbb::blocked_range<size_t> &range) {
+    [&its, &is_on_sides, &skip_indicies](const tbb::blocked_range<size_t> &range) {
         for (size_t i = range.begin(); i < range.end(); ++i) {
             if (is_all_on_one_side(its.indices[i], is_on_sides)) 
-                skip_triangle[i] = 1;
+                skip_indicies[i] = true;
         }
     }); // END parallel for
-    for (size_t i = 0; i < skip_triangle.size(); ++i)
-        if (skip_triangle[i])
-            skip_indicies[i] = true;
 }
 
 indexed_triangle_set Slic3r::its_mask(const indexed_triangle_set &its,

src/libslic3r/Format/bbs_3mf.cpp

@@ -1340,7 +1340,7 @@ void PlateData::parse_filament_info(GCodeProcessorResult *result)
 
         bool _handle_start_relationship(const char** attributes, unsigned int num_attributes);
 
-        void _generate_current_object_list(std::vector<Component> &sub_objects, Id object_id, IdToCurrentObjectMap& current_objects);
+        bool _generate_current_object_list(std::vector<Component> &sub_objects, Id object_id, IdToCurrentObjectMap& current_objects);
         bool _generate_volumes_new(ModelObject& object, const std::vector<Component> &sub_objects, const ObjectMetadata::VolumeMetadataList& volumes, ConfigSubstitutionContext& config_substitutions);
         //bool _generate_volumes(ModelObject& object, const Geometry& geometry, const ObjectMetadata::VolumeMetadataList& volumes, ConfigSubstitutionContext& config_substitutions);
 
@@ -2055,7 +2055,8 @@ void PlateData::parse_filament_info(GCodeProcessorResult *result)
                         return false;
                     }
                     std::vector<Component> object_id_list;
-                    _generate_current_object_list(object_id_list, object.first, m_current_objects);
+                    if (!_generate_current_object_list(object_id_list, object.first, m_current_objects))
+                        return false;
 
                     ObjectMetadata::VolumeMetadataList volumes;
                     ObjectMetadata::VolumeMetadataList* volumes_ptr = nullptr;
@@ -2154,7 +2155,8 @@ void PlateData::parse_filament_info(GCodeProcessorResult *result)
             }*/
 
             std::vector<Component> object_id_list;
-            _generate_current_object_list(object_id_list, object.first, m_current_objects);
+            if (!_generate_current_object_list(object_id_list, object.first, m_current_objects))
+                return false;
 
             ObjectMetadata::VolumeMetadataList volumes;
             ObjectMetadata::VolumeMetadataList* volumes_ptr = nullptr;
@@ -5002,31 +5004,45 @@ void PlateData::parse_filament_info(GCodeProcessorResult *result)
         return true;
     }
 
-    void _BBS_3MF_Importer::_generate_current_object_list(std::vector<Component> &sub_objects, Id object_id, IdToCurrentObjectMap &current_objects)
+    bool _BBS_3MF_Importer::_generate_current_object_list(std::vector<Component> &sub_objects, Id object_id, IdToCurrentObjectMap &current_objects)
     {
-        std::list<std::pair<Component, Transform3d>> id_list;
-        id_list.push_back(std::make_pair(Component(object_id, Transform3d::Identity()), Transform3d::Identity()));
+        // A chain of component references longer than the number of objects has to visit an object
+        // twice, so the component graph contains a cycle and the expansion below would not stop.
+        const size_t max_depth = current_objects.size();
+        // An acyclic graph may still expand exponentially, so bound the number of expanded components
+        // as well. Way above the number of parts of any real object.
+        static constexpr size_t max_components = 100000;
 
+        std::list<std::tuple<Component, Transform3d, size_t>> id_list;
+        id_list.push_back(std::make_tuple(Component(object_id, Transform3d::Identity()), Transform3d::Identity(), 0));
+
+        size_t num_components = 0;
         while (!id_list.empty())
         {
             auto current_item = id_list.front();
-            Component current_id = current_item.first;
+            Component current_id = std::get<0>(current_item);
             id_list.pop_front();
+            if (std::get<2>(current_item) > max_depth || ++ num_components > max_components) {
+                add_error("invalid 3mf: cyclic or too deeply nested components");
+                sub_objects.clear();
+                return false;
+            }
             IdToCurrentObjectMap::iterator current_object = current_objects.find(current_id.object_id);
             if (current_object != current_objects.end()) {
                 //found one
                 if (!current_object->second.components.empty()) {
                     for (const Component &comp : current_object->second.components) {
-                        id_list.push_back(std::pair(comp, current_item.second * comp.transform));
+                        id_list.push_back(std::make_tuple(comp, std::get<1>(current_item) * comp.transform, std::get<2>(current_item) + 1));
                     }
                 }
                 else if (!(current_object->second.geometry.empty())) {
                     //CurrentObject* ptr = &(current_objects[current_id]);
                     //CurrentObject* ptr2 = &(current_object->second);
-                    sub_objects.push_back({ current_object->first, current_item.second});
+                    sub_objects.push_back({ current_object->first, std::get<1>(current_item)});
                 }
             }
         }
+        return true;
     }
 
     bool _BBS_3MF_Importer::_generate_volumes_new(ModelObject& object, const std::vector<Component> &sub_objects, const ObjectMetadata::VolumeMetadataList& volumes, ConfigSubstitutionContext& config_substitutions)

src/libslic3r/MultiMaterialSegmentation.cpp

@@ -1378,66 +1378,55 @@ static inline std::vector<std::vector<ExPolygons>> segmentation_top_and_bottom_l
         return out;
     };
 
-    // The layers are processed in groups of "granularity" layers. A layer projects its shells up to "granularity"
-    // layers away, thus a group may write into the slots of its neighbor groups. The even and the odd groups
-    // therefore write into two disjoint halves of the output vectors (the 2nd half is offset by num_layers) and
-    // both halves are merged below. The group index has to be derived from the layer index and not from the extent
-    // of the TBB sub-range: tbb::blocked_range bisects at midpoints, thus a sub-range neither starts at a multiple
-    // of the grain size nor covers a whole group, and two sub-ranges of one group would append into a single
-    // ExPolygons concurrently. Iterating over the groups keeps every group on a single thread, in ascending order.
-    const size_t num_groups = (num_layers + size_t(granularity) - 1) / size_t(granularity);
-    tbb::parallel_for(tbb::blocked_range<size_t>(0, num_groups, 1), [&granularity, &num_layers, &num_facets_states, &layer_color_stat, &top_raw, &triangles_by_color_top,
-                                                                    &throw_on_cancel_callback, &input_expolygons, &bottom_raw, &triangles_by_color_bottom,
-                                                                    &shell_triangles_by_color_top, &shell_triangles_by_color_bottom](const tbb::blocked_range<size_t> &range) {
-        for (size_t group_idx = range.begin(); group_idx < range.end(); ++ group_idx) {
-            const size_t layer_idx_offset = (group_idx & 1) * num_layers;
-            const size_t layer_idx_begin  = group_idx * size_t(granularity);
-            const size_t layer_idx_end    = std::min(num_layers, layer_idx_begin + size_t(granularity));
-            for (size_t layer_idx = layer_idx_begin; layer_idx < layer_idx_end; ++ layer_idx) {
-                for (size_t color_idx = 0; color_idx < num_facets_states; ++color_idx) {
-                    throw_on_cancel_callback();
-                    LayerColorStat stat = layer_color_stat(layer_idx, color_idx);
-                    if (std::vector<Polygons> &top = top_raw[color_idx]; ! top.empty() && ! top[layer_idx].empty())
-                        if (ExPolygons top_ex = union_ex(top[layer_idx]); ! top_ex.empty()) {
-                            // Clean up thin projections. They are not printable anyways.
-                            top_ex = opening_ex(top_ex, stat.small_region_threshold);
-                            if (! top_ex.empty()) {
-                                append(triangles_by_color_top[color_idx][layer_idx + layer_idx_offset], top_ex);
-                                float offset = 0.f;
-                                ExPolygons layer_slices_trimmed = input_expolygons[layer_idx];
-                                for (int last_idx = int(layer_idx) - 1; last_idx > std::max(int(layer_idx - stat.top_shell_layers), int(0)); --last_idx) {
-                                    //BBS: offset width should be 2*spacing to avoid too narrow area which has overlap of wall line
-                                    //offset -= stat.extrusion_width ;
-                                    offset -= (stat.extrusion_spacing + stat.extrusion_width);
-                                    layer_slices_trimmed = intersection_ex(layer_slices_trimmed, input_expolygons[last_idx]);
-                                    ExPolygons last = opening_ex(intersection_ex(top_ex, offset_ex(layer_slices_trimmed, offset)), stat.small_region_threshold);
-                                    if (last.empty())
-                                        break;
-                                    append(shell_triangles_by_color_top[color_idx][last_idx + layer_idx_offset], std::move(last));
-                                }
+    tbb::parallel_for(tbb::blocked_range<size_t>(0, num_layers, granularity), [&granularity, &num_layers, &num_facets_states, &layer_color_stat, &top_raw, &triangles_by_color_top,
+                                                                               &throw_on_cancel_callback, &input_expolygons, &bottom_raw, &triangles_by_color_bottom,
+                                                                               &shell_triangles_by_color_top, &shell_triangles_by_color_bottom](const tbb::blocked_range<size_t> &range) {
+        size_t group_idx   = range.begin() / granularity;
+        size_t layer_idx_offset = (group_idx & 1) * num_layers;
+        for (size_t layer_idx = range.begin(); layer_idx < range.end(); ++ layer_idx) {
+            for (size_t color_idx = 0; color_idx < num_facets_states; ++color_idx) {
+                throw_on_cancel_callback();
+                LayerColorStat stat = layer_color_stat(layer_idx, color_idx);
+                if (std::vector<Polygons> &top = top_raw[color_idx]; ! top.empty() && ! top[layer_idx].empty())
+                    if (ExPolygons top_ex = union_ex(top[layer_idx]); ! top_ex.empty()) {
+                        // Clean up thin projections. They are not printable anyways.
+                        top_ex = opening_ex(top_ex, stat.small_region_threshold);
+                        if (! top_ex.empty()) {
+                            append(triangles_by_color_top[color_idx][layer_idx + layer_idx_offset], top_ex);
+                            float offset = 0.f;
+                            ExPolygons layer_slices_trimmed = input_expolygons[layer_idx];
+                            for (int last_idx = int(layer_idx) - 1; last_idx > std::max(int(layer_idx - stat.top_shell_layers), int(0)); --last_idx) {
+                                //BBS: offset width should be 2*spacing to avoid too narrow area which has overlap of wall line
+                                //offset -= stat.extrusion_width ;
+                                offset -= (stat.extrusion_spacing + stat.extrusion_width);
+                                layer_slices_trimmed = intersection_ex(layer_slices_trimmed, input_expolygons[last_idx]);
+                                ExPolygons last = opening_ex(intersection_ex(top_ex, offset_ex(layer_slices_trimmed, offset)), stat.small_region_threshold);
+                                if (last.empty())
+                                    break;
+                                append(shell_triangles_by_color_top[color_idx][last_idx + layer_idx_offset], std::move(last));
                             }
                         }
-                    if (std::vector<Polygons> &bottom = bottom_raw[color_idx]; ! bottom.empty() && ! bottom[layer_idx].empty())
-                        if (ExPolygons bottom_ex = union_ex(bottom[layer_idx]); ! bottom_ex.empty()) {
-                            // Clean up thin projections. They are not printable anyways.
-                            bottom_ex = opening_ex(bottom_ex, stat.small_region_threshold);
-                            if (! bottom_ex.empty()) {
-                                append(triangles_by_color_bottom[color_idx][layer_idx + layer_idx_offset], bottom_ex);
-                                float offset = 0.f;
-                                ExPolygons layer_slices_trimmed = input_expolygons[layer_idx];
-                                for (size_t last_idx = layer_idx + 1; last_idx < std::min(layer_idx + stat.bottom_shell_layers, num_layers); ++last_idx) {
-                                    //BBS: offset width should be 2*spacing to avoid too narrow area which has overlap of wall line
-                                    //offset -= stat.extrusion_width;
-                                    offset -= (stat.extrusion_spacing + stat.extrusion_width);
-                                    layer_slices_trimmed = intersection_ex(layer_slices_trimmed, input_expolygons[last_idx]);
-                                    ExPolygons last = opening_ex(intersection_ex(bottom_ex, offset_ex(layer_slices_trimmed, offset)), stat.small_region_threshold);
-                                    if (last.empty())
-                                        break;
-                                    append(shell_triangles_by_color_bottom[color_idx][last_idx + layer_idx_offset], std::move(last));
-                                }
+                    }
+                if (std::vector<Polygons> &bottom = bottom_raw[color_idx]; ! bottom.empty() && ! bottom[layer_idx].empty())
+                    if (ExPolygons bottom_ex = union_ex(bottom[layer_idx]); ! bottom_ex.empty()) {
+                        // Clean up thin projections. They are not printable anyways.
+                        bottom_ex = opening_ex(bottom_ex, stat.small_region_threshold);
+                        if (! bottom_ex.empty()) {
+                            append(triangles_by_color_bottom[color_idx][layer_idx + layer_idx_offset], bottom_ex);
+                            float offset = 0.f;
+                            ExPolygons layer_slices_trimmed = input_expolygons[layer_idx];
+                            for (size_t last_idx = layer_idx + 1; last_idx < std::min(layer_idx + stat.bottom_shell_layers, num_layers); ++last_idx) {
+                                //BBS: offset width should be 2*spacing to avoid too narrow area which has overlap of wall line
+                                //offset -= stat.extrusion_width;
+                                offset -= (stat.extrusion_spacing + stat.extrusion_width);
+                                layer_slices_trimmed = intersection_ex(layer_slices_trimmed, input_expolygons[last_idx]);
+                                ExPolygons last = opening_ex(intersection_ex(bottom_ex, offset_ex(layer_slices_trimmed, offset)), stat.small_region_threshold);
+                                if (last.empty())
+                                    break;
+                                append(shell_triangles_by_color_bottom[color_idx][last_idx + layer_idx_offset], std::move(last));
                             }
                         }
-                }
+                    }
             }
         }
     });

src/libslic3r/Support/TreeModelVolumes.cpp

@@ -424,16 +424,8 @@ void TreeModelVolumes::calculateCollision(const coord_t radius, const LayerIndex
         [this](size_t i, size_t j) { return m_layer_outlines[i].second.size() < m_layer_outlines[j].second.size(); });
 
     // Layer range for which the collisions will be calculated.
-    // Another thread may have advanced getMaxCalculatedLayer() past max_layer_idx after this calculation
-    // was requested. Bail out in that case, otherwise the layer range would be negative and allocating
-    // it would throw std::length_error out of a parallel task.
-    const LayerIndex            start_layer = 1 + m_collision_cache.getMaxCalculatedLayer(radius);
-    if (start_layer > max_layer_idx) {
-        BOOST_LOG_TRIVIAL(debug) << "Requested calculation for value already calculated ?";
-        return;
-    }
     LayerPolygonCache           data;
-    data.allocate(start_layer, max_layer_idx + 1);
+    data.allocate(m_collision_cache.getMaxCalculatedLayer(radius) + 1, max_layer_idx + 1);
 
     const bool                  calculate_placable = m_support_rests_on_model && radius == 0;
     LayerPolygonCache           data_placeable;
@@ -812,12 +804,6 @@ void TreeModelVolumes::calculateWallRestrictions(const std::vector<RadiusLayerPa
             const coord_t    radius             = keys[key_idx].first;
             const LayerIndex max_required_layer = keys[key_idx].second;
             const coord_t    min_layer_bottom   = std::max(1, m_wall_restrictions_cache.getMaxCalculatedLayer(radius));
-            if (min_layer_bottom > max_required_layer) {
-                // Another thread has calculated this range in the meantime. Continuing would make
-                // buffer_size negative and allocating it would throw std::length_error.
-                BOOST_LOG_TRIVIAL(debug) << "Requested calculation for value already calculated ?";
-                continue;
-            }
             const size_t     buffer_size        = max_required_layer + 1 - min_layer_bottom;
             std::vector<Polygons> data(buffer_size, Polygons{});
             std::vector<Polygons> data_min;

src/libslic3r/Thread.cpp

@@ -12,7 +12,6 @@
 #include <thread>
 #include <tbb/parallel_for.h>
 #include <tbb/task_arena.h>
-#include <tbb/task_scheduler_observer.h>
 
 #include "Thread.hpp"
 #include "Utils.hpp"
@@ -213,71 +212,70 @@ bool is_main_thread_active()
 	return get_main_thread_id() == boost::this_thread::get_id();
 }
 
-// Name the current TBB worker thread and set its locale to "C", so that the G-code generator
-// produces "." as a decimal separator. Called once per worker thread, before it runs its first task.
-static void setup_tbb_worker_thread()
-{
-	static std::atomic<size_t> s_worker_idx{ 0 };
-	std::ostringstream name;
-	name << "slic3r_tbb_" << (1 + s_worker_idx.fetch_add(1, std::memory_order_relaxed));
-	set_current_thread_name(name.str().c_str());
-#ifdef _WIN32
-	_configthreadlocale(_ENABLE_PER_THREAD_LOCALE);
-	std::setlocale(LC_ALL, "C");
-#else
-	// We are leaking some memory here, because the newlocale() produced memory will never be released.
-	// This is not a problem though, as there will be a maximum one worker thread created per physical thread.
-	uselocale(newlocale(
-#ifdef __APPLE__
-		LC_ALL_MASK
-#else // some Unix / Linux / BSD
-		LC_ALL
-#endif
-		, "C", nullptr));
-#endif
-}
-
-// Sets up the TBB worker threads of the arena of the thread, which activated the observation.
-// A worker sets itself up on entry to the arena, before it executes its first task, thus unlike a barrier
-// inside a parallel_for, this does not depend on TBB running any number of tasks simultaneously.
-class TBBWorkerThreadSetupObserver : public tbb::task_scheduler_observer
-{
-public:
-	TBBWorkerThreadSetupObserver() { this->observe(true); }
-
-	void on_scheduler_entry(bool is_worker) override
-	{
-		// Leave the external threads (the calling / UI thread) alone, their name and locale must not be modified here.
-		if (! is_worker)
-			return;
-		// A worker thread enters an arena many times, while its name and locale have to be set just once.
-		static thread_local bool initialized = false;
-		if (initialized)
-			return;
-		initialized = true;
-		setup_tbb_worker_thread();
-	}
-};
-
-// Name the threads of the Intel TBB thread pool by an index and set their locale to "C"
-// for the G-code generator to produce "." as a decimal separator.
-// Formerly all the worker threads were caught inside a single parallel_for, which was held on a condition
-// variable barrier until max_concurrency() of its chunks were running. TBB guarantees no such simultaneity,
-// thus the barrier was able to block the slicing threads indefinitely. The TBB scheduler observer below
-// sets each worker up on its own, thus no two chunks have to run at the same time.
+// Spawn (n - 1) worker threads on Intel TBB thread pool and name them by an index and a system thread ID.
+// Also it sets locale of the worker threads to "C" for the G-code generator to produce "." as a decimal separator.
 void name_tbb_thread_pool_threads_set_locale()
 {
+	static bool initialized = false;
+	if (initialized)
+		return;
+	initialized = true;
+
+	// see GH issue #5661 PrusaSlicer hangs on Linux when run with non standard task affinity
+	// TBB will respect the task affinity mask on Linux and spawn less threads than std::thread::hardware_concurrency().
+//	const size_t nthreads_hw = std::thread::hardware_concurrency();
+	const size_t nthreads_hw = tbb::this_task_arena::max_concurrency();
+	size_t       nthreads    = nthreads_hw;
+
 #ifdef SLIC3R_PROFILE
 	// Shiny profiler is not thread safe, thus disable parallelization.
 	disable_multi_threading();
+	nthreads = 1;
 #endif
 
-	// An observer is local to the arena of the thread which activates it, thus one observer is registered
-	// per calling thread. Being function local and thread local, it is also initialized exactly once per
-	// thread without a race. It is intentionally never destroyed, as it has to stay alive as long as the
-	// TBB scheduler may notify it, which includes the shutdown of the process.
-	static thread_local tbb::task_scheduler_observer *observer = new TBBWorkerThreadSetupObserver();
-	(void)observer;
+	size_t                  nthreads_running(0);
+	std::condition_variable cv;
+	std::mutex				cv_m;
+	auto					master_thread_id = std::this_thread::get_id();
+    tbb::parallel_for(
+        tbb::blocked_range<size_t>(0, nthreads, 1),
+        [&nthreads_running, nthreads, &master_thread_id, &cv, &cv_m](const tbb::blocked_range<size_t> &range) {
+        	assert(range.begin() + 1 == range.end());
+			if (std::unique_lock<std::mutex> lk(cv_m);  ++nthreads_running == nthreads) {
+				lk.unlock();
+        		// All threads are spinning.
+        		// Wake them up.
+    			cv.notify_all();
+        	} else {
+        		// Wait for the last thread to wake the others.
+			    cv.wait(lk, [&nthreads_running, nthreads]{return nthreads_running == nthreads;});
+        	}
+        	auto thread_id = std::this_thread::get_id();
+			if (thread_id == master_thread_id) {
+				// The calling thread runs the 0'th task.
+				assert(range.begin() == 0);
+			} else {
+				assert(range.begin() > 0);
+				std::ostringstream name;
+		        name << "slic3r_tbb_" << range.begin();
+		        set_current_thread_name(name.str().c_str());
+		        // Set locales of the worker thread to "C".
+#ifdef _WIN32
+			    _configthreadlocale(_ENABLE_PER_THREAD_LOCALE);
+			    std::setlocale(LC_ALL, "C");
+#else
+				// We are leaking some memory here, because the newlocale() produced memory will never be released.
+				// This is not a problem though, as there will be a maximum one worker thread created per physical thread.
+				uselocale(newlocale(
+#ifdef __APPLE__
+					LC_ALL_MASK
+#else // some Unix / Linux / BSD
+					LC_ALL
+#endif
+					, "C", nullptr));
+#endif
+    		}
+        });
 }
 
 }

src/libslic3r/TriangleSetSampling.cpp

@@ -28,10 +28,6 @@ TriangleSetSamples sample_its_uniform_parallel(size_t samples_count, const index
         area_sum_to_triangle_idx[area_sum] = t_idx;
     }
 
-    if (area_sum_to_triangle_idx.empty())
-        // No triangle to sample from.
-        return {};
-
     std::mt19937_64 mersenne_engine { 27644437 };
     // random numbers on interval [0, 1)
     std::uniform_real_distribution<double> fdistribution;
@@ -54,10 +50,7 @@ TriangleSetSamples sample_its_uniform_parallel(size_t samples_count, const index
                     tbb::blocked_range<size_t> r) {
                 for (size_t s_idx = r.begin(); s_idx < r.end(); ++s_idx) {
                     double t_sample = random_samples[s_idx].x() * area_sum;
-                    // The keys of area_sum_to_triangle_idx are accumulated areas in double precision, while area_sum
-                    // is a float, thus t_sample may reach or exceed the largest key and upper_bound() may return end().
-                    auto   t_it    = area_sum_to_triangle_idx.upper_bound(t_sample);
-                    size_t t_idx   = (t_it == area_sum_to_triangle_idx.end() ? std::prev(t_it) : t_it)->second;
+                    size_t t_idx = area_sum_to_triangle_idx.upper_bound(t_sample)->second;
 
                     double sq_u = std::sqrt(random_samples[s_idx].y());
                     double v = random_samples[s_idx].z();

tests/libslic3r/test_3mf.cpp

@@ -27,6 +27,7 @@
 #include <Eigen/Geometry>
 #include <type_traits> // for std::enable_if_t
 #include <typeinfo>    // for typeid
+#include <regex>
 
 namespace Catch {
     template <typename T>
@@ -321,6 +322,30 @@ TEST_CASE("A project with a plate id below 1 fails to load", "[3mf][Regression]"
     REQUIRE_FALSE(loaded);
 }
 
+TEST_CASE("A project whose components reference themselves fails to load", "[3mf][Regression]")
+{
+    ScopedTemporaryFile temp(".3mf");
+    store_painted_cube(temp.string());
+
+    // Point the component back at the object that holds it. Expanding that reference used to push
+    // into the work list forever, growing it until the process ran out of memory.
+    REQUIRE(rewrite_3mf_entries(temp.string(), [](std::string& name, std::string& data) {
+        if (!boost::algorithm::ends_with(name, "3dmodel.model"))
+            return false;
+        std::smatch match;
+        if (!std::regex_search(data, match, std::regex("<object id=\"([0-9]+)\"[^>]*>\\s*<components")))
+            return false;
+        data = std::regex_replace(data, std::regex("objectid=\"[0-9]+\""), "objectid=\"" + match[1].str() + "\"");
+        return true;
+    }));
+
+    ScopedTemporaryDir backup_dir("orca_cycle_dst");
+    Model              model;
+    bool               loaded = true;
+    REQUIRE_NOTHROW(loaded = load_project(temp.string(), model, backup_dir));
+    REQUIRE_FALSE(loaded);
+}
+
 TEST_CASE("A project with malformed paint data loads without the damaged facet", "[3mf][Regression]")
 {
     ScopedTemporaryFile temp(".3mf");