fix bug for csc prediction.

src/c_api.cpp

@@ -171,7 +171,7 @@ public:
 
   void Predict(int num_iteration, int predict_type, int nrow,
                std::function<std::vector<std::pair<int, double>>(int row_idx)> get_row_fun,
-               const char* parameter,
+               const IOConfig& config,
                double* out_result, int64_t* out_len) {
     std::lock_guard<std::mutex> lock(mutex_);
     bool is_predict_leaf = false;
@@ -183,9 +183,7 @@ public:
     } else {
       is_raw_score = false;
     }
-    auto param = ConfigBase::Str2Map(parameter);
-    IOConfig config;
-    config.Set(param);
+
     Predictor predictor(boosting_.get(), num_iteration, is_raw_score, is_predict_leaf,
                         config.pred_early_stop, config.pred_early_stop_freq, config.pred_early_stop_margin);
     int64_t num_preb_in_one_row = boosting_->NumPredictOneRow(num_iteration, is_predict_leaf);
@@ -204,7 +202,7 @@ public:
   }
 
   void Predict(int num_iteration, int predict_type, const char* data_filename,
-               int data_has_header, const char* parameter,
+               int data_has_header, const IOConfig& config,
                const char* result_filename) {
     std::lock_guard<std::mutex> lock(mutex_);
     bool is_predict_leaf = false;
@@ -216,9 +214,6 @@ public:
     } else {
       is_raw_score = false;
     }
-    auto param = ConfigBase::Str2Map(parameter);
-    IOConfig config;
-    config.Set(param);
     Predictor predictor(boosting_.get(), num_iteration, is_raw_score, is_predict_leaf,
                         config.pred_early_stop, config.pred_early_stop_freq, config.pred_early_stop_margin);
     bool bool_data_has_header = data_has_header > 0 ? true : false;
@@ -981,9 +976,15 @@ int LGBM_BoosterPredictForFile(BoosterHandle handle,
                                const char* parameter,
                                const char* result_filename) {
   API_BEGIN();
+  auto param = ConfigBase::Str2Map(parameter);
+  OverallConfig config;
+  config.Set(param);
+  if (config.num_threads > 0) {
+    omp_set_num_threads(config.num_threads);
+  }
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
   ref_booster->Predict(num_iteration, predict_type, data_filename, data_has_header,
-                       parameter, result_filename);
+                       config.io_config, result_filename);
   API_END();
 }
 
@@ -1014,11 +1015,17 @@ int LGBM_BoosterPredictForCSR(BoosterHandle handle,
                               int64_t* out_len,
                               double* out_result) {
   API_BEGIN();
+  auto param = ConfigBase::Str2Map(parameter);
+  OverallConfig config;
+  config.Set(param);
+  if (config.num_threads > 0) {
+    omp_set_num_threads(config.num_threads);
+  }
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
   auto get_row_fun = RowFunctionFromCSR(indptr, indptr_type, indices, data, data_type, nindptr, nelem);
   int nrow = static_cast<int>(nindptr - 1);
   ref_booster->Predict(num_iteration, predict_type, nrow, get_row_fun,
-                       parameter, out_result, out_len);
+                       config.io_config, out_result, out_len);
   API_END();
 }
 
@@ -1038,23 +1045,38 @@ int LGBM_BoosterPredictForCSC(BoosterHandle handle,
                               double* out_result) {
   API_BEGIN();
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
+  auto param = ConfigBase::Str2Map(parameter);
+  OverallConfig config;
+  config.Set(param);
+  if (config.num_threads > 0) {
+    omp_set_num_threads(config.num_threads);
+  }
+  int num_threads = 1;
+  #pragma omp parallel
+  #pragma omp master
+  {
+    num_threads = omp_get_num_threads();
+  }
   int ncol = static_cast<int>(ncol_ptr - 1);
-  std::vector<CSC_RowIterator> iterators;
-  for (int j = 0; j < ncol; ++j) {
-    iterators.emplace_back(col_ptr, col_ptr_type, indices, data, data_type, ncol_ptr, nelem, j);
+  std::vector<std::vector<CSC_RowIterator>> iterators(num_threads, std::vector<CSC_RowIterator>());
+  for (int i = 0; i < num_threads; ++i) {
+    for (int j = 0; j < ncol; ++j) {
+      iterators[i].emplace_back(col_ptr, col_ptr_type, indices, data, data_type, ncol_ptr, nelem, j);
+    }
   }
   std::function<std::vector<std::pair<int, double>>(int row_idx)> get_row_fun =
     [&iterators, ncol] (int i) {
     std::vector<std::pair<int, double>> one_row;
+    const int tid = omp_get_thread_num();
     for (int j = 0; j < ncol; ++j) {
-      auto val = iterators[j].Get(i);
+      auto val = iterators[tid][j].Get(i);
       if (std::fabs(val) > kEpsilon) {
         one_row.emplace_back(j, val);
       }
     }
     return one_row;
   };
-  ref_booster->Predict(num_iteration, predict_type, static_cast<int>(num_row), get_row_fun, parameter,
+  ref_booster->Predict(num_iteration, predict_type, static_cast<int>(num_row), get_row_fun, config.io_config,
                        out_result, out_len);
   API_END();
 }
@@ -1071,10 +1093,16 @@ int LGBM_BoosterPredictForMat(BoosterHandle handle,
                               int64_t* out_len,
                               double* out_result) {
   API_BEGIN();
+  auto param = ConfigBase::Str2Map(parameter);
+  OverallConfig config;
+  config.Set(param);
+  if (config.num_threads > 0) {
+    omp_set_num_threads(config.num_threads);
+  }
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
   auto get_row_fun = RowPairFunctionFromDenseMatric(data, nrow, ncol, data_type, is_row_major);
   ref_booster->Predict(num_iteration, predict_type, nrow, get_row_fun,
-                       parameter, out_result, out_len);
+                       config.io_config, out_result, out_len);
   API_END();
 }