From 17c1dae962a008efa67b55e5147dcedfa23a68f6 Mon Sep 17 00:00:00 2001
From: hong <43953930+phlrain@users.noreply.github.com>
Date: Wed, 11 Aug 2021 10:00:03 +0800
Subject: [PATCH] Add no need output to gc check list (#34754)

* add not used output var to gc_check_list; test=develop

* add useless output to gc check list; test=develop
---
 paddle/fluid/framework/new_exec.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/paddle/fluid/framework/new_exec.h b/paddle/fluid/framework/new_exec.h
index cecbdb45a9c..defa7a96733 100644
--- a/paddle/fluid/framework/new_exec.h
+++ b/paddle/fluid/framework/new_exec.h
@@ -500,6 +500,17 @@ class InterpreterCore {
       }
       vec_instruction_[i].next_instruction_.direct_run_ = filter_next;
 
+      // checkout ouput
+      for (auto& item : vec_instruction_[i].output_index_) {
+        for (auto id : item.second) {
+          if (input_var2op_info_[id].size() == 0) {
+            // output var not be used by any kernel
+            vec_instruction_[i].gc_check_var_list.push_back(id);
+            global_scope.vec_meta_info_[id].var_ref_count_++;
+          }
+        }
+      }
+
       for (auto inst_id : filter_next) {
         dependecy_count_[inst_id]++;
       }
-- 
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