fix broadcast bug

paddle/fluid/framework/parallel_executor.cc

@@ -153,7 +153,6 @@ void ParallelExecutor::BCastParamsToGPUs(
     if (main_var == nullptr || !main_var->IsType<LoDTensor>()) {
       continue;
     }
-    VLOG(3) << "run broadcast " << var << " " << var_dev_id;
 
     auto &main_tensor = main_var->Get<LoDTensor>();
     auto &dims = main_tensor.dims();
@@ -184,8 +183,16 @@ void ParallelExecutor::BCastParamsToGPUs(
         platform::NCCLGroupGuard guard;
         for (size_t i = 0; i < member_->places_.size(); ++i) {
           auto &nccl_ctx = member_->nccl_ctxs_->at(member_->places_[i]);
-          platform::dynload::ncclBcast(buffers[i], numel, data_type, 0,
-                                       nccl_ctx.comm_, nccl_ctx.stream());
+          if (initializing) {
+            platform::dynload::ncclBcast(buffers[i], numel, data_type, 0,
+                                         nccl_ctx.comm_, nccl_ctx.stream());
+          } else {
+            if (static_cast<size_t>(var_dev_id)) {
+              platform::dynload::ncclBcast(buffers[i], numel, data_type,
+                                           var_dev_id, nccl_ctx.comm_,
+                                           nccl_ctx.stream());
+            }
+          }
         }
         member_->nccl_ctxs_->WaitAll();
       }