From 1d8c2391e8b413a981b625b691b33a5237d4b6f7 Mon Sep 17 00:00:00 2001
From: tqchen <tianqi.tchen@gmail.com>
Date: Mon, 18 Aug 2014 14:58:30 -0700
Subject: [PATCH] update tree maker to make it more robust

---
 python/README.md                  | 1 +
 src/tree/updater_colmaker-inl.hpp | 3 ++-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/python/README.md b/python/README.md
index cf59ba9ab..4aceb7d5e 100644
--- a/python/README.md
+++ b/python/README.md
@@ -3,3 +3,4 @@ python wrapper for xgboost using ctypes
 see example for usage
 
 to make the python module, type make in the root directory of project
+
diff --git a/src/tree/updater_colmaker-inl.hpp b/src/tree/updater_colmaker-inl.hpp
index eb5ff85fc..3645e53ce 100644
--- a/src/tree/updater_colmaker-inl.hpp
+++ b/src/tree/updater_colmaker-inl.hpp
@@ -271,7 +271,8 @@ class ColMaker: public IUpdater<FMatrix> {
       }
       // start enumeration
       const unsigned nsize = static_cast<unsigned>(feat_set.size());
-      #pragma omp parallel for schedule(dynamic, 1)
+      const int batch_size = std::max(static_cast<int>(nsize / this->nthread / 32), 1);
+      #pragma omp parallel for schedule(dynamic, batch_size)
       for (unsigned i = 0; i < nsize; ++i) {
         const unsigned fid = feat_set[i];
         const int tid = omp_get_thread_num();