From 3858f458ea5a3103c75f1d68107f023449874db7 Mon Sep 17 00:00:00 2001
From: ShenLiang <shenliang03@baidu.com>
Date: Fri, 29 Jan 2021 18:28:23 +0800
Subject: [PATCH] rm Singleton of reducer (#30775)

---
 paddle/fluid/imperative/reducer.cc |  8 --------
 paddle/fluid/imperative/reducer.h  | 28 ----------------------------
 paddle/fluid/pybind/imperative.cc  | 15 +++++----------
 3 files changed, 5 insertions(+), 46 deletions(-)

diff --git a/paddle/fluid/imperative/reducer.cc b/paddle/fluid/imperative/reducer.cc
index 6801cac9526..0c33cdd7c85 100644
--- a/paddle/fluid/imperative/reducer.cc
+++ b/paddle/fluid/imperative/reducer.cc
@@ -41,8 +41,6 @@ namespace paddle {
 namespace imperative {
 
 #if defined(PADDLE_WITH_NCCL)
-std::shared_ptr<Reducer> Reducer::s_instance_ = NULL;
-
 template <typename DeviceContext, typename T>
 static void ConcatTensorsForAllReduce(
     const DeviceContext &context,
@@ -225,14 +223,8 @@ Reducer::Reducer(const std::vector<std::shared_ptr<imperative::VarBase>> &vars,
             })));
     var_index_map_[var->GradVarBase()->SharedVar().get()] = global_var_index;
   }
-
-  std::call_once(once_flag_, []() {
-    std::atexit([]() { Reducer::GetInstance()->ReleaseReducer(); });
-  });
 }
 
-void Reducer::ReleaseReducer() { parallel_ctx_.reset(); }
-
 void Reducer::InitializeDenseGroups(
     const std::vector<size_t> &variable_indices_, Group *p_group) {
   int64_t all_length = 0;
diff --git a/paddle/fluid/imperative/reducer.h b/paddle/fluid/imperative/reducer.h
index 9bb528bbdef..90c4cdb3c6a 100644
--- a/paddle/fluid/imperative/reducer.h
+++ b/paddle/fluid/imperative/reducer.h
@@ -108,44 +108,16 @@ class Reducer {
 
   void AddDistHook(size_t var_index);
 
-  // void MarkDenseVarReady(size_t var_index);
-
-  // void MarkSparseVarReady(size_t var_index);
-
   void MarkVarReady(const size_t var_index, const bool is_used_var);
 
   void MarkGroupReady(size_t group_index);
 
   void FinalizeBackward();
 
-  void ReleaseReducer();
-
   std::vector<std::vector<size_t>> RebuildGruops();
 
   inline bool NeedRebuildGroup() { return !has_rebuilt_group_; }
 
-  // Reducer Singleton
-  static std::shared_ptr<Reducer> SetInstance(
-      const std::vector<std::shared_ptr<imperative::VarBase>>& vars,
-      const std::vector<std::vector<size_t>>& group_indices,
-      const std::vector<bool>& is_sparse_gradient,
-      std::shared_ptr<imperative::ParallelContext> parallel_ctx,
-      const std::vector<size_t>& group_size_limits, bool find_unused_vars) {
-    if (NULL == s_instance_) {
-      s_instance_.reset(new paddle::imperative::Reducer(
-          vars, group_indices, is_sparse_gradient, parallel_ctx,
-          group_size_limits, find_unused_vars));
-    }
-    return s_instance_;
-  }
-
-  static std::shared_ptr<Reducer> GetInstance() {
-    PADDLE_ENFORCE_EQ(
-        s_instance_ != NULL, true,
-        platform::errors::InvalidArgument("Reducer is not initialized."));
-    return s_instance_;
-  }
-
  private:
   std::vector<std::shared_ptr<imperative::VarBase>> vars_;
   std::vector<std::vector<size_t>> group_indices_;
diff --git a/paddle/fluid/pybind/imperative.cc b/paddle/fluid/pybind/imperative.cc
index 87aa989c411..cceae74f1dc 100644
--- a/paddle/fluid/pybind/imperative.cc
+++ b/paddle/fluid/pybind/imperative.cc
@@ -1390,16 +1390,11 @@ void BindImperative(py::module *m_ptr) {
 
   py::class_<imperative::Reducer, std::shared_ptr<imperative::Reducer>>(
       m, "Reducer", R"DOC()DOC")
-      .def(py::init([](
-          const std::vector<std::shared_ptr<imperative::VarBase>> &vars,
-          const std::vector<std::vector<size_t>> &group_indices,
-          const std::vector<bool> &is_sparse_gradient,
-          std::shared_ptr<imperative::ParallelContext> parallel_ctx,
-          const std::vector<size_t> &group_size_limits, bool find_unused_vars) {
-        return imperative::Reducer::SetInstance(
-            vars, group_indices, is_sparse_gradient, parallel_ctx,
-            group_size_limits, find_unused_vars);
-      }))
+      .def(py::init<const std::vector<std::shared_ptr<imperative::VarBase>> &,
+                    const std::vector<std::vector<size_t>> &,
+                    const std::vector<bool> &,
+                    std::shared_ptr<imperative::ParallelContext>,
+                    const std::vector<size_t> &, bool>())
       .def("prepare_for_backward", &imperative::Reducer::PrepareForBackward,
            py::arg("vars"), py::call_guard<py::gil_scoped_release>());
 
-- 
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