From 5c2d7a18c92b445ba897d4b0b4859508ae720883 Mon Sep 17 00:00:00 2001
From: Jiaming Yuan <jm.yuan@outlook.com>
Date: Tue, 15 Jun 2021 14:08:26 +0800
Subject: [PATCH] Parallel model dump for trees. (#7040)

---
 src/gbm/gbtree_model.h | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/src/gbm/gbtree_model.h b/src/gbm/gbtree_model.h
index 2d07ec198a79..c5e05c0157af 100644
--- a/src/gbm/gbtree_model.h
+++ b/src/gbm/gbtree_model.h
@@ -17,6 +17,8 @@
 #include <string>
 #include <vector>
 
+#include "../common/threading_utils.h"
+
 namespace xgboost {
 
 class Json;
@@ -107,12 +109,12 @@ struct GBTreeModel : public Model {
   void SaveModel(Json* p_out) const override;
   void LoadModel(Json const& p_out) override;
 
-  std::vector<std::string> DumpModel(const FeatureMap& fmap, bool with_stats,
+  std::vector<std::string> DumpModel(const FeatureMap &fmap, bool with_stats,
                                      std::string format) const {
-    std::vector<std::string> dump;
-    for (const auto & tree : trees) {
-      dump.push_back(tree->DumpModel(fmap, with_stats, format));
-    }
+    std::vector<std::string> dump(trees.size());
+    common::ParallelFor(static_cast<omp_ulong>(trees.size()), [&](size_t i) {
+      dump[i] = trees[i]->DumpModel(fmap, with_stats, format);
+    });
     return dump;
   }
   void CommitModel(std::vector<std::unique_ptr<RegTree> >&& new_trees,