simplify and hide bcast_params

Author: panyx0718

paddle/fluid/framework/parallel_executor.cc

@@ -209,30 +209,9 @@ ParallelExecutor::ParallelExecutor(
 
 void ParallelExecutor::BCastParamsToDevices(
     const std::unordered_set<std::string> &vars) const {
-  // the initializing bcast, all vars would be bcast from device(0),
-  // otherwise
-  // bcast from the specified device.
-  bool initializing = member_->executor_ ? false : true;
+  // the initializing bcast, all vars would be bcast from device(0).
   for (auto &var : vars) {
-    int var_dev_id = -1;
-    if (member_->executor_) {
-      auto &sharded_var_device =
-          member_->executor_->Graph().Get<details::ShardedVarDevice>(
-              details::kShardedVarDevice);
-      if (sharded_var_device.find(var) != sharded_var_device.end()) {
-        var_dev_id = sharded_var_device.at(var);
-      }
-    }
-
-    if (!initializing && var_dev_id == -1) continue;
-
-    framework::Variable *main_var = nullptr;
-    if (initializing) {
-      main_var = member_->local_scopes_[0]->FindVar(var);
-    } else {
-      main_var = member_->local_scopes_[var_dev_id]->FindVar(var);
-    }
-
+    framework::Variable *main_var = member_->local_scopes_[0]->FindVar(var);
     if (main_var == nullptr || !main_var->IsType<LoDTensor>()) {
       continue;
     }
@@ -248,8 +227,7 @@ void ParallelExecutor::BCastParamsToDevices(
         auto place = member_->places_[i];
         void *buffer;
 
-        if ((initializing && i == 0) ||
-            (!initializing && static_cast<int>(i) == var_dev_id)) {
+        if (i == 0) {
           buffer = const_cast<void *>(main_tensor.data<void>());
         } else {
           auto local_scope = member_->local_scopes_[i];
@@ -266,29 +244,18 @@ void ParallelExecutor::BCastParamsToDevices(
         platform::NCCLGroupGuard guard;
         for (size_t i = 0; i < member_->places_.size(); ++i) {
           auto &nccl_ctx = member_->nccl_ctxs_->at(member_->places_[i]);
-          if (initializing) {
-            platform::dynload::ncclBcast(buffers[i], numel, data_type, 0,
-                                         nccl_ctx.comm_, nccl_ctx.stream());
-          } else {
-            if (var_dev_id >= 0) {
-              platform::dynload::ncclBcast(buffers[i], numel, data_type,
-                                           var_dev_id, nccl_ctx.comm_,
-                                           nccl_ctx.stream());
-            }
-          }
+          platform::dynload::ncclBcast(buffers[i], numel, data_type, 0,
+                                       nccl_ctx.comm_, nccl_ctx.stream());
         }
         member_->nccl_ctxs_->WaitAll();
       }
-
 #else
       PADDLE_THROW("Not compiled with CUDA");
 #endif
     } else {
       platform::CPUPlace cpu;
       for (size_t i = 0; i < member_->places_.size(); ++i) {
-        if ((initializing && i == 0) ||
-            (!initializing && static_cast<int>(i) == var_dev_id))
-          continue;
+        if (i == 0) continue;
 
         auto local_scope = member_->local_scopes_[i];
         auto *t = local_scope->Var(var)->GetMutable<LoDTensor>();

paddle/fluid/framework/parallel_executor.h

@@ -66,9 +66,9 @@ class ParallelExecutor {
   void Run(const std::vector<std::string> &fetch_tensors,
            const std::string &fetched_var_name);
 
+ private:
   void BCastParamsToDevices(const std::unordered_set<std::string> &vars) const;
 
- private:
   ParallelExecutorPrivate *member_;
 };