Check for correct updater sequence

dmlc · Apr 10, 2020 · 78b2d37 · 78b2d37
1 parent 5ce2f18
commit 78b2d37
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diff --git a/src/gbm/gbtree.cc b/src/gbm/gbtree.cc
@@ -267,6 +267,11 @@ void GBTree::BoostNewTrees(HostDeviceVector<GradientPair>* gpair,
   // create the trees
   for (int i = 0; i < tparam_.num_parallel_tree; ++i) {
     if (tparam_.process_type == TreeProcessType::kDefault) {
+      CHECK(!updaters_.front()->CanModifyTree())
+          << "Updater: `" << updaters_.front()->Name() << "` "
+          << "can not be used to create new trees. "
+          << "Set `process_type` to `update` if you want to update existing "
+             "trees.";
       // create new tree
       std::unique_ptr<RegTree> ptr(new RegTree());
       ptr->param.UpdateAllowUnknown(this->cfg_);

diff --git a/tests/cpp/gbm/test_gbtree.cc b/tests/cpp/gbm/test_gbtree.cc
@@ -63,6 +63,10 @@ TEST(GBTree, WrongUpdater) {
   // Hist can not be used for updating tree.
   learner->SetParams(Args{{"tree_method", "hist"}, {"process_type", "update"}});
   ASSERT_THROW(learner->UpdateOneIter(0, p_dmat), dmlc::Error);
+  // Prune can not be used for learning new tree.
+  learner->SetParams(
+      Args{{"tree_method", "prune"}, {"process_type", "default"}});
+  ASSERT_THROW(learner->UpdateOneIter(0, p_dmat), dmlc::Error);
 }
 
 #ifdef XGBOOST_USE_CUDA