fix bug for multi-val-bin construction (#2841)

* fix

* Update multi_val_sparse_bin.hpp

src/io/bin.cpp

@@ -694,8 +694,7 @@ namespace LightGBM {
                                                     int num_bin,
                                                     double estimate_element_per_row) {
     size_t estimate_total_entries =
-        static_cast<size_t>(estimate_element_per_row * 1.1) *
-        static_cast<size_t>(num_data);
+        static_cast<size_t>(estimate_element_per_row * 1.1 * num_data);
     if (estimate_total_entries <= std::numeric_limits<uint16_t>::max()) {
       if (num_bin <= 256) {
         return new MultiValSparseBin<uint16_t, uint8_t>(

src/io/multi_val_sparse_bin.hpp

@@ -24,9 +24,7 @@ class MultiValSparseBin : public MultiValBin {
         num_bin_(num_bin),
         estimate_element_per_row_(estimate_element_per_row) {
     row_ptr_.resize(num_data_ + 1, 0);
-    INDEX_T estimate_num_data =
-        static_cast<INDEX_T>(estimate_element_per_row_ * 1.1) *
-        static_cast<INDEX_T>(num_data_);
+    INDEX_T estimate_num_data = static_cast<INDEX_T>(estimate_element_per_row_ * 1.1 * num_data_);
     int num_threads = 1;
 #pragma omp parallel
 #pragma omp master
@@ -73,7 +71,7 @@ class MultiValSparseBin : public MultiValBin {
 
   void MergeData(const INDEX_T* sizes) {
     Common::FunctionTimer fun_time("MultiValSparseBin::MergeData", global_timer);
-    for (INDEX_T i = 0; i < static_cast<INDEX_T>(num_data_); ++i) {
+    for (data_size_t i = 0; i < num_data_; ++i) {
       row_ptr_[i + 1] += row_ptr_[i];
     }
     if (t_data_.size() > 0) {
@@ -83,7 +81,7 @@ class MultiValSparseBin : public MultiValBin {
         offsets[tid + 1] = offsets[tid] + sizes[tid + 1];
       }
       data_.resize(row_ptr_[num_data_]);
-#pragma omp parallel for schedule(static)
+#pragma omp parallel for schedule(static, 1)
       for (int tid = 0; tid < static_cast<int>(t_data_.size()); ++tid) {
         std::copy_n(t_data_[tid].data(), sizes[tid + 1],
                     data_.data() + offsets[tid]);
@@ -199,8 +197,7 @@ class MultiValSparseBin : public MultiValBin {
     auto other_bin = dynamic_cast<const MultiValSparseBin<INDEX_T, VAL_T>*>(full_bin);
     row_ptr_.resize(num_data_ + 1, 0);
     INDEX_T estimate_num_data =
-        static_cast<INDEX_T>(estimate_element_per_row_ * 1.1) *
-        static_cast<INDEX_T>(num_data_);
+        static_cast<INDEX_T>(estimate_element_per_row_ * 1.1 * num_data_);
     data_.clear();
     data_.reserve(estimate_num_data);
     for (data_size_t i = 0; i < num_used_indices; ++i) {
@@ -224,8 +221,7 @@ class MultiValSparseBin : public MultiValBin {
     num_bin_ = num_bin;
     estimate_element_per_row_ = estimate_element_per_row;
     INDEX_T estimate_num_data =
-        static_cast<INDEX_T>(estimate_element_per_row_ * 1.1) *
-        static_cast<INDEX_T>(num_data_);
+        static_cast<INDEX_T>(estimate_element_per_row_ * 1.1 * num_data_);
     size_t npart = 1 + t_data_.size();
     INDEX_T avg_num_data = static_cast<INDEX_T>(estimate_num_data / npart);
     if (static_cast<INDEX_T>(data_.size()) < avg_num_data) {