From 72aef6b16861181db327ab0adfc8d4de329c8ffe Mon Sep 17 00:00:00 2001
From: Qiao Longfei <qiaolongfei@baidu.com>
Date: Sun, 28 Oct 2018 17:44:39 +0800
Subject: [PATCH] sum selected rows check empty

---
 paddle/fluid/operators/sum_op.h | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/paddle/fluid/operators/sum_op.h b/paddle/fluid/operators/sum_op.h
index d3c905c0b8..f6e12dfc76 100644
--- a/paddle/fluid/operators/sum_op.h
+++ b/paddle/fluid/operators/sum_op.h
@@ -116,8 +116,22 @@ class SumKernel : public framework::OpKernel<T> {
       auto *out = context.Output<SelectedRows>("Out");
       out->mutable_rows()->clear();
 
-      math::scatter::MergeAdd<DeviceContext, T> merge_add;
-      merge_add(context.template device_context<DeviceContext>(), inputs, out);
+      bool has_data = false;
+      for (auto &in : inputs) {
+        if (in->rows().size() > 0) {
+          has_data = true;
+          break;
+        }
+      }
+      if (has_data) {
+        math::scatter::MergeAdd<DeviceContext, T> merge_add;
+        merge_add(context.template device_context<DeviceContext>(), inputs,
+                  out);
+      } else {
+        // no data, just set a empty out tensor.
+        out->mutable_value()->mutable_data<T>(framework::make_ddim({0}),
+                                              context.GetPlace());
+      }
     } else if (out_var->IsType<framework::LoDTensorArray>()) {
       auto &out_array = *out_var->GetMutable<framework::LoDTensorArray>();
       for (size_t i = in_place ? 1 : 0; i < in_vars.size(); ++i) {
-- 
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