diff --git a/deepspeech/exps/u2/model.py b/deepspeech/exps/u2/model.py
index dd62f537e85597949c6397975c3b22efbd0d7fbd..add225912ea0de0b27de7f13e42f04a5fe55c07b 100644
--- a/deepspeech/exps/u2/model.py
+++ b/deepspeech/exps/u2/model.py
@@ -532,7 +532,7 @@ class U2Tester(U2Trainer):
                 # 1. Encoder
                 encoder_out, encoder_mask = self.model._forward_encoder(
                     feat, feats_length)  # (B, maxlen, encoder_dim)
-                maxlen = encoder_out.size(1)
+                maxlen = encoder_out.shape[1]
                 ctc_probs = self.model.ctc.log_softmax(
                     encoder_out)  # (1, maxlen, vocab_size)
 
@@ -598,10 +598,20 @@ class U2Tester(U2Trainer):
 
     def export(self):
         infer_model, input_spec = self.load_inferspec()
-        assert isinstance(input_spec, list), type(input_spec)
+        # assert isinstance(input_spec, list), type(input_spec)
         infer_model.eval()
-        static_model = paddle.jit.to_static(infer_model, input_spec=input_spec)
-        logger.info(f"Export code: {static_model.forward.code}")
+        #static_model = paddle.jit.to_static(infer_model., input_spec=input_spec)
+        
+        static_model = paddle.jit.to_static(
+            infer_model.forward_attention_decoder, 
+            input_spec=[
+             paddle.static.InputSpec(shape=[1, None],dtype='int32'),
+             paddle.static.InputSpec(shape=[1],dtype='int32'),
+             paddle.static.InputSpec(shape=[1, None, 256],dtype='int32'),
+            ]
+        )
+        logger.info(f"Export code: {static_model}")
+        
         paddle.jit.save(static_model, self.args.export_path)
 
     def run_export(self):
diff --git a/deepspeech/models/u2.py b/deepspeech/models/u2.py
index 6b266bdb430cd2403dc447f22016a844a13afb76..a9f37833beca699ff65f9bed4fe493b27e62dcca 100644
--- a/deepspeech/models/u2.py
+++ b/deepspeech/models/u2.py
@@ -299,8 +299,8 @@ class U2BaseModel(nn.Module):
             speech, speech_lengths, decoding_chunk_size,
             num_decoding_left_chunks,
             simulate_streaming)  # (B, maxlen, encoder_dim)
-        maxlen = encoder_out.size(1)
-        encoder_dim = encoder_out.size(2)
+        maxlen = encoder_out.shape[1]
+        encoder_dim = encoder_out.shape[2]
         running_size = batch_size * beam_size
         encoder_out = encoder_out.unsqueeze(1).repeat(1, beam_size, 1, 1).view(
             running_size, maxlen, encoder_dim)  # (B*N, maxlen, encoder_dim)
@@ -405,7 +405,7 @@ class U2BaseModel(nn.Module):
         encoder_out, encoder_mask = self._forward_encoder(
             speech, speech_lengths, decoding_chunk_size,
             num_decoding_left_chunks, simulate_streaming)
-        maxlen = encoder_out.size(1)
+        maxlen = encoder_out.shape[1]
         # (TODO Hui Zhang): bool no support reduce_sum
         # encoder_out_lens = encoder_mask.squeeze(1).sum(1)
         encoder_out_lens = encoder_mask.squeeze(1).astype(paddle.int).sum(1)
@@ -455,7 +455,7 @@ class U2BaseModel(nn.Module):
             speech, speech_lengths, decoding_chunk_size,
             num_decoding_left_chunks,
             simulate_streaming)  # (B, maxlen, encoder_dim)
-        maxlen = encoder_out.size(1)
+        maxlen = encoder_out.shape[1]
         ctc_probs = self.ctc.log_softmax(encoder_out)  # (1, maxlen, vocab_size)
         ctc_probs = ctc_probs.squeeze(0)
         # cur_hyps: (prefix, (blank_ending_score, none_blank_ending_score))
@@ -578,7 +578,7 @@ class U2BaseModel(nn.Module):
         hyps_lens = hyps_lens + 1  # Add <sos> at begining
         encoder_out = encoder_out.repeat(beam_size, 1, 1)
         encoder_mask = paddle.ones(
-            (beam_size, 1, encoder_out.size(1)), dtype=paddle.bool)
+            (beam_size, 1, encoder_out.shape[1]), dtype=paddle.bool)
         decoder_out, _ = self.decoder(
             encoder_out, encoder_mask, hyps_pad,
             hyps_lens)  # (beam_size, max_hyps_len, vocab_size)
@@ -624,7 +624,7 @@ class U2BaseModel(nn.Module):
         """
         return self.eos
 
-    @jit.export
+    # @jit.export
     def forward_encoder_chunk(
             self,
             xs: paddle.Tensor,
@@ -654,9 +654,7 @@ class U2BaseModel(nn.Module):
             xs, offset, required_cache_size, subsampling_cache,
             elayers_output_cache, conformer_cnn_cache)
 
-    # @jit.export([
-    #         paddle.static.InputSpec(shape=[1, None, feat_dim],dtype='float32'),  # audio feat, [B,T,D]
-    #     ])
+    # @jit.export
     def ctc_activation(self, xs: paddle.Tensor) -> paddle.Tensor:
         """ Export interface for c++ call, apply linear transform and log
             softmax before ctc
@@ -667,7 +665,7 @@ class U2BaseModel(nn.Module):
         """
         return self.ctc.log_softmax(xs)
 
-    @jit.export
+    # @jit.export
     def forward_attention_decoder(
             self,
             hyps: paddle.Tensor,
@@ -683,13 +681,14 @@ class U2BaseModel(nn.Module):
         Returns:
             paddle.Tensor: decoder output, (B, L)
         """
-        assert encoder_out.size(0) == 1
-        num_hyps = hyps.size(0)
-        assert hyps_lens.size(0) == num_hyps
-        encoder_out = encoder_out.repeat(num_hyps, 1, 1)
+        assert encoder_out.shape[0] == 1
+        num_hyps = hyps.shape[0]
+        assert hyps_lens.shape[0] == num_hyps
+        # encoder_out = encoder_out.repeat(num_hyps, 1, 1)
+        encoder_out = encoder_out.tile([num_hyps, 1, 1])
         # (B, 1, T)
         encoder_mask = paddle.ones(
-            [num_hyps, 1, encoder_out.size(1)], dtype=paddle.bool)
+            [num_hyps, 1, encoder_out.shape[1]], dtype=paddle.bool)
         # (num_hyps, max_hyps_len, vocab_size)
         decoder_out, _ = self.decoder(encoder_out, encoder_mask, hyps,
                                       hyps_lens)
@@ -744,7 +743,7 @@ class U2BaseModel(nn.Module):
         Returns:
             List[List[int]]: transcripts.
         """
-        batch_size = feats.size(0)
+        batch_size = feats.shape[0]
         if decoding_method in ['ctc_prefix_beam_search',
                                'attention_rescoring'] and batch_size > 1:
             logger.fatal(
@@ -772,7 +771,7 @@ class U2BaseModel(nn.Module):
         # result in List[int], change it to List[List[int]] for compatible
         # with other batch decoding mode
         elif decoding_method == 'ctc_prefix_beam_search':
-            assert feats.size(0) == 1
+            assert feats.shape[0] == 1
             hyp = self.ctc_prefix_beam_search(
                 feats,
                 feats_lengths,
@@ -782,7 +781,7 @@ class U2BaseModel(nn.Module):
                 simulate_streaming=simulate_streaming)
             hyps = [hyp]
         elif decoding_method == 'attention_rescoring':
-            assert feats.size(0) == 1
+            assert feats.shape[0] == 1
             hyp = self.attention_rescoring(
                 feats,
                 feats_lengths,
@@ -922,7 +921,7 @@ class U2InferModel(U2Model):
         Returns:
             List[List[int]]: best path result
         """
-        return self.ctc_greedy_search(
+        return self.attention_rescoring(
             feats,
             feats_lengths,
             decoding_chunk_size=decoding_chunk_size,
diff --git a/deepspeech/modules/attention.py b/deepspeech/modules/attention.py
index 4401a4a5552fa26e8141ef07c4fef1da095ec483..ac1e9b75b38118f566bdce0e4c4a70c222ac09f4 100644
--- a/deepspeech/modules/attention.py
+++ b/deepspeech/modules/attention.py
@@ -70,7 +70,7 @@ class MultiHeadedAttention(nn.Layer):
             paddle.Tensor: Transformed value tensor, size
                 (#batch, n_head, time2, d_k).
         """
-        n_batch = query.size(0)
+        n_batch = query.shape[0]
         q = self.linear_q(query).view(n_batch, -1, self.h, self.d_k)
         k = self.linear_k(key).view(n_batch, -1, self.h, self.d_k)
         v = self.linear_v(value).view(n_batch, -1, self.h, self.d_k)
@@ -96,7 +96,7 @@ class MultiHeadedAttention(nn.Layer):
             paddle.Tensor: Transformed value weighted 
                 by the attention score, (#batch, time1, d_model).
         """
-        n_batch = value.size(0)
+        n_batch = value.shape[0]
         if mask is not None:
             mask = mask.unsqueeze(1).eq(0)  # (batch, 1, *, time2)
             scores = scores.masked_fill(mask, -float('inf'))
@@ -172,15 +172,15 @@ class RelPositionMultiHeadedAttention(MultiHeadedAttention):
             paddle.Tensor: Output tensor. (batch, head, time1, time1)
         """
         zero_pad = paddle.zeros(
-            (x.size(0), x.size(1), x.size(2), 1), dtype=x.dtype)
+            (x.shape[0], x.shape[1], x.shape[2], 1), dtype=x.dtype)
         x_padded = paddle.cat([zero_pad, x], dim=-1)
 
-        x_padded = x_padded.view(x.size(0), x.size(1), x.size(3) + 1, x.size(2))
+        x_padded = x_padded.view(x.shape[0], x.shape[1], x.shape[3] + 1, x.shape[2])
         x = x_padded[:, :, 1:].view_as(x)  # [B, H, T1, T1]
 
         if zero_triu:
-            ones = paddle.ones((x.size(2), x.size(3)))
-            x = x * paddle.tril(ones, x.size(3) - x.size(2))[None, None, :, :]
+            ones = paddle.ones((x.shape[2], x.shape[3]))
+            x = x * paddle.tril(ones, x.shape[3] - x.shape[2])[None, None, :, :]
 
         return x
 
@@ -205,7 +205,7 @@ class RelPositionMultiHeadedAttention(MultiHeadedAttention):
         q, k, v = self.forward_qkv(query, key, value)
         q = q.transpose([0, 2, 1, 3])  # (batch, time1, head, d_k)
 
-        n_batch_pos = pos_emb.size(0)
+        n_batch_pos = pos_emb.shape[0]
         p = self.linear_pos(pos_emb).view(n_batch_pos, -1, self.h, self.d_k)
         p = p.transpose([0, 2, 1, 3])  # (batch, head, time1, d_k)
 
diff --git a/deepspeech/modules/decoder.py b/deepspeech/modules/decoder.py
index 696a6315b98fc3220c6717eb2f9b9e8aebd080a9..b4eb46f20c5ba2a4b6843f6c753ebade634cc518 100644
--- a/deepspeech/modules/decoder.py
+++ b/deepspeech/modules/decoder.py
@@ -122,7 +122,7 @@ class TransformerDecoder(nn.Module):
         # tgt_mask: (B, 1, L)
         tgt_mask = (make_non_pad_mask(ys_in_lens).unsqueeze(1))
         # m: (1, L, L)
-        m = subsequent_mask(tgt_mask.size(-1)).unsqueeze(0)
+        m = subsequent_mask(tgt_mask.shape[-1]).unsqueeze(0)
         # tgt_mask: (B, L, L)
         # TODO(Hui Zhang): not support & for tensor
         # tgt_mask = tgt_mask & m
diff --git a/deepspeech/modules/embedding.py b/deepspeech/modules/embedding.py
index 98b4e1291415176dd36d54de185ef8acc68d9701..fbbda023c613a5328ac6a1e87938ed2428ff98aa 100644
--- a/deepspeech/modules/embedding.py
+++ b/deepspeech/modules/embedding.py
@@ -68,7 +68,7 @@ class PositionalEncoding(nn.Layer):
             paddle.Tensor: for compatibility to RelPositionalEncoding, (batch=1, time, ...)
         """
         T = x.shape[1]
-        assert offset + x.size(1) < self.max_len
+        assert offset + x.shape[1] < self.max_len
         #TODO(Hui Zhang): using T = x.size(1), __getitem__ not support Tensor
         pos_emb = self.pe[:, offset:offset + T]
         x = x * self.xscale + pos_emb
@@ -114,7 +114,7 @@ class RelPositionalEncoding(PositionalEncoding):
             paddle.Tensor: Encoded tensor (batch, time, `*`).
             paddle.Tensor: Positional embedding tensor (1, time, `*`).
         """
-        assert offset + x.size(1) < self.max_len
+        assert offset + x.shape[1] < self.max_len
         x = x * self.xscale
         #TODO(Hui Zhang): using x.size(1), __getitem__ not support Tensor
         pos_emb = self.pe[:, offset:offset + x.shape[1]]
diff --git a/deepspeech/utils/tensor_utils.py b/deepspeech/utils/tensor_utils.py
index 58f958c4bf30340e51d087d8a9f138c8128cf03a..2e60599911a4e984cc03f3aa0fbcabf1745b11ea 100644
--- a/deepspeech/utils/tensor_utils.py
+++ b/deepspeech/utils/tensor_utils.py
@@ -65,11 +65,11 @@ def pad_sequence(sequences: List[paddle.Tensor],
 
     # assuming trailing dimensions and type of all the Tensors
     # in sequences are same and fetching those from sequences[0]
-    max_size = sequences[0].size()
+    max_size = sequences[0].shape
     # (TODO Hui Zhang): slice not supprot `end==start`
     # trailing_dims = max_size[1:]
     trailing_dims = max_size[1:] if max_size.ndim >= 2 else ()
-    max_len = max([s.size(0) for s in sequences])
+    max_len = max([s.shape[0] for s in sequences])
     if batch_first:
         out_dims = (len(sequences), max_len) + trailing_dims
     else:
@@ -77,7 +77,7 @@ def pad_sequence(sequences: List[paddle.Tensor],
 
     out_tensor = sequences[0].new_full(out_dims, padding_value)
     for i, tensor in enumerate(sequences):
-        length = tensor.size(0)
+        length = tensor.shape[0]
         # use index notation to prevent duplicate references to the tensor
         if batch_first:
             out_tensor[i, :length, ...] = tensor
@@ -125,7 +125,7 @@ def add_sos_eos(ys_pad: paddle.Tensor, sos: int, eos: int,
     #ys_in = [paddle.cat([_sos, y], dim=0) for y in ys]
     #ys_out = [paddle.cat([y, _eos], dim=0) for y in ys]
     #return pad_sequence(ys_in, padding_value=eos), pad_sequence(ys_out, padding_value=ignore_id)
-    B = ys_pad.size(0)
+    B = ys_pad.shape[0]
     _sos = paddle.ones([B, 1], dtype=ys_pad.dtype) * sos
     _eos = paddle.ones([B, 1], dtype=ys_pad.dtype) * eos
     ys_in = paddle.cat([_sos, ys_pad], dim=1)
@@ -152,7 +152,7 @@ def th_accuracy(pad_outputs: paddle.Tensor,
         float: Accuracy value (0.0 - 1.0).
     """
     pad_pred = pad_outputs.view(
-        pad_targets.size(0), pad_targets.size(1), pad_outputs.size(1)).argmax(2)
+        pad_targets.shape[0], pad_targets.size(1), pad_outputs.size(1)).argmax(2)
     mask = pad_targets != ignore_label
     #TODO(Hui Zhang): sum not support bool type
     # numerator = paddle.sum(