From 8d44f5f5246a9ccf3309c612cdb03bd95a9f0585 Mon Sep 17 00:00:00 2001
From: Laurent Perron <lperron@google.com>
Date: Thu, 3 Aug 2023 10:12:38 -0700
Subject: [PATCH] fix race and subsequent crash

---
 ortools/sat/cp_model_lns.cc | 12 +++++-------
 ortools/sat/cp_model_lns.h  |  1 -
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/ortools/sat/cp_model_lns.cc b/ortools/sat/cp_model_lns.cc
index cc4e3af004..875aa061e9 100644
--- a/ortools/sat/cp_model_lns.cc
+++ b/ortools/sat/cp_model_lns.cc
@@ -2028,21 +2028,19 @@ Neighborhood SchedulingTimeWindowNeighborhoodGenerator::Generate(
 Neighborhood SchedulingResourceWindowsNeighborhoodGenerator::Generate(
     const CpSolverResponse& initial_solution, double difficulty,
     absl::BitGenRef random) {
-  intervals_to_relax_.clear();
+  std::vector<int> intervals_to_relax;
   for (const std::vector<int>& intervals : intervals_in_constraints_) {
     const std::vector<int> selected_indices = SelectIndicesInRandomTimeWindow(
         intervals, helper_.ModelProto(), initial_solution, difficulty, random);
     for (const int index : selected_indices) {
-      intervals_to_relax_.insert(intervals[index]);
+      intervals_to_relax.push_back(intervals[index]);
     }
   }
 
-  if (intervals_to_relax_.empty()) return helper_.FullNeighborhood();
-
-  const std::vector<int> intervals(
-      {intervals_to_relax_.begin(), intervals_to_relax_.end()});
+  if (intervals_to_relax.empty()) return helper_.FullNeighborhood();
+  gtl::STLSortAndRemoveDuplicates(&intervals_to_relax);
   return GenerateSchedulingNeighborhoodFromRelaxedIntervals(
-      intervals, initial_solution, random, helper_);
+      intervals_to_relax, initial_solution, random, helper_);
 }
 
 Neighborhood RandomRectanglesPackingNeighborhoodGenerator::Generate(
diff --git a/ortools/sat/cp_model_lns.h b/ortools/sat/cp_model_lns.h
index 23fb5fff8b..f478bdf08d 100644
--- a/ortools/sat/cp_model_lns.h
+++ b/ortools/sat/cp_model_lns.h
@@ -679,7 +679,6 @@ class SchedulingResourceWindowsNeighborhoodGenerator
 
  private:
   const std::vector<std::vector<int>> intervals_in_constraints_;
-  absl::flat_hash_set<int> intervals_to_relax_;
 };
 
 // Only make sense for problems with no_overlap_2d constraints. This select a