add log

paddle/fluid/operators/optimizers/adam_op.h

@@ -357,6 +357,9 @@ class AdamOpKernel : public framework::OpKernel<T> {
       if (inner_op_parallelism > 1 &&
           FLAGS_min_param_size_to_use_multithread > 0 &&
           param.numel() > FLAGS_min_param_size_to_use_multithread) {
+        VLOG(3) << "use multi thread, inner_op_parallelism="
+                << inner_op_parallelism << " min_param_size_to_use_multithread"
+                << FLAGS_min_param_size_to_use_multithread;
         std::vector<std::future<void>> fs;
         int64_t block_size = param.numel() / inner_op_parallelism;
         for (int i = 0; i < inner_op_parallelism; ++i) {