Resizing embedding matrix before sending it to the optimizer. (#3532)

* Resizing embedding matrix after sending it to the optimizer prevents from updating the newly resized matrix.

* Remove space for style matter

examples/run_language_modeling.py

@@ -233,6 +233,9 @@ def train(args, train_dataset, model: PreTrainedModel, tokenizer: PreTrainedToke
     else:
         t_total = len(train_dataloader) // args.gradient_accumulation_steps * args.num_train_epochs
 
+    model = model.module if hasattr(model, "module") else model  # Take care of distributed/parallel training
+    model.resize_token_embeddings(len(tokenizer))
+
     # Prepare optimizer and schedule (linear warmup and decay)
     no_decay = ["bias", "LayerNorm.weight"]
     optimizer_grouped_parameters = [
@@ -309,9 +312,6 @@ def train(args, train_dataset, model: PreTrainedModel, tokenizer: PreTrainedToke
 
     tr_loss, logging_loss = 0.0, 0.0
 
-    model_to_resize = model.module if hasattr(model, "module") else model  # Take care of distributed/parallel training
-    model_to_resize.resize_token_embeddings(len(tokenizer))
-
     model.zero_grad()
     train_iterator = trange(
         epochs_trained, int(args.num_train_epochs), desc="Epoch", disable=args.local_rank not in [-1, 0]