fix a multi-thread bug in pred_contrib

include/LightGBM/boosting.h

@@ -257,8 +257,9 @@ class LIGHTGBM_EXPORT Boosting {
   /*!
   * \brief Initial work for the prediction
   * \param num_iteration number of used iteration
+  * \param is_pred_contrib
   */
-  virtual void InitPredict(int num_iteration) = 0;
+  virtual void InitPredict(int num_iteration, bool is_pred_contrib) = 0;
 
   /*!
   * \brief Name of submodel

include/LightGBM/tree.h

@@ -203,6 +203,8 @@ class Tree {
     (*decision_type) |= (input << 2);
   }
 
+  void RecomputeMaxDepth();
+
 private:
 
   std::string NumericalDecisionIfElse(int node) const;
@@ -313,8 +315,6 @@ class Tree {
 
   double ExpectedValue() const;
 
-  int MaxDepth();
-
   /*! \brief This is used fill in leaf_depth_ after reloading a model*/
   inline void RecomputeLeafDepths(int node = 0, int depth = 0);
 
@@ -390,6 +390,7 @@ class Tree {
   /*! \brief Depth for leaves */
   std::vector<int> leaf_depth_;
   double shrinkage_;
+  int max_depth_;
 };
 
 inline void Tree::Split(int leaf, int feature, int real_feature,
@@ -468,10 +469,10 @@ inline void Tree::PredictContrib(const double* feature_values, int num_features,
   output[num_features] += ExpectedValue();
   // Run the recursion with preallocated space for the unique path data
   if (num_leaves_ > 1) {
-    const int max_path_len = MaxDepth() + 1;
-    PathElement *unique_path_data = new PathElement[(max_path_len*(max_path_len + 1)) / 2];
-    TreeSHAP(feature_values, output, 0, 0, unique_path_data, 1, 1, -1);
-    delete[] unique_path_data;
+    CHECK(max_depth_ >= 0);
+    const int max_path_len = max_depth_ + 1;
+    std::vector<PathElement> unique_path_data(max_path_len*(max_path_len + 1) / 2);
+    TreeSHAP(feature_values, output, 0, 0, unique_path_data.data(), 1, 1, -1);
   }
 }
 

src/application/predictor.hpp

@@ -55,7 +55,7 @@ class Predictor {
     {
       num_threads_ = omp_get_num_threads();
     }
-    boosting->InitPredict(num_iteration);
+    boosting->InitPredict(num_iteration, is_predict_contrib);
     boosting_ = boosting;
     num_pred_one_row_ = boosting_->NumPredictOneRow(num_iteration, is_predict_leaf_index, is_predict_contrib);
     num_feature_ = boosting_->MaxFeatureIdx() + 1;

src/boosting/gbdt.h

@@ -291,11 +291,17 @@ class GBDT : public GBDTBase {
   */
   inline int NumberOfClasses() const override { return num_class_; }
 
-  inline void InitPredict(int num_iteration) override {
+  inline void InitPredict(int num_iteration, bool is_pred_contrib) override {
     num_iteration_for_pred_ = static_cast<int>(models_.size()) / num_tree_per_iteration_;
     if (num_iteration > 0) {
       num_iteration_for_pred_ = std::min(num_iteration, num_iteration_for_pred_);
     }
+    if (is_pred_contrib) {
+      #pragma omp parallel for schedule(static)
+      for (int i = 0; i < static_cast<int>(models_.size()); ++i) {
+        models_[i]->RecomputeMaxDepth();
+      }
+    }
   }
 
   inline double GetLeafValue(int tree_idx, int leaf_idx) const override {

src/io/tree.cpp

@@ -41,6 +41,7 @@ Tree::Tree(int max_leaves)
   num_cat_ = 0;
   cat_boundaries_.push_back(0);
   cat_boundaries_inner_.push_back(0);
+  max_depth_ = -1;
 }
 
 Tree::~Tree() {
@@ -584,6 +585,7 @@ Tree::Tree(const char* str, size_t* used_len) {
   } else {
     shrinkage_ = 1.0f;
   }
+  max_depth_ = -1;
 }
 
 void Tree::ExtendPath(PathElement *unique_path, int unique_depth,
@@ -652,7 +654,7 @@ void Tree::TreeSHAP(const double *feature_values, double *phi,
                     double parent_one_fraction, int parent_feature_index) const {
 
   // extend the unique path
-  PathElement *unique_path = parent_unique_path + unique_depth;
+  PathElement* unique_path = parent_unique_path + unique_depth;
   if (unique_depth > 0) std::copy(parent_unique_path, parent_unique_path + unique_depth, unique_path);
   ExtendPath(unique_path, unique_depth, parent_zero_fraction,
              parent_one_fraction, parent_feature_index);
@@ -706,14 +708,18 @@ double Tree::ExpectedValue() const {
   return exp_value;
 }
 
-int Tree::MaxDepth() {
-  if (leaf_depth_.size() == 0) RecomputeLeafDepths();
-  if (num_leaves_ == 1) return 0;
-  int max_depth = 0;
-  for (int i = 0; i < num_leaves(); ++i) {
-    if (max_depth < leaf_depth_[i]) max_depth = leaf_depth_[i];
+void Tree::RecomputeMaxDepth() {
+  if (num_leaves_ == 1) {
+    max_depth_ = 0;
+  } else {
+    if (leaf_depth_.size() == 0) {
+      RecomputeLeafDepths(0, 0);
+    }
+    max_depth_ = leaf_depth_[0];
+    for (int i = 1; i < num_leaves(); ++i) {
+      if (max_depth_ < leaf_depth_[i]) max_depth_ = leaf_depth_[i];
+    }
   }
-  return max_depth;
 }
 
 }  // namespace LightGBM