import torch
import time
from dataclasses import dataclass
from opentelemetry import trace
from transformers import AutoTokenizer, AutoModelForSeq2SeqLM, PreTrainedTokenizerBase
from typing import Optional, Tuple, List, Type, Dict
from text_generation_server.utils.chunks import concat_text_chunks
from text_generation_server.utils.tokens import batch_top_tokens
from text_generation_server.models import Model
from text_generation_server.models.types import (
GeneratedText,
Batch,
Generation,
Tokens,
)
from text_generation_server.pb import generate_pb2
from text_generation_server.utils import NextTokenChooser, StoppingCriteria, Sampling
tracer = trace.get_tracer(__name__)
@dataclass
class Seq2SeqLMBatch(Batch):
batch_id: int
requests: List[generate_pb2.Request]
requests_idx_mapping: Dict[int, int]
# Encoder values
input_ids: Optional[torch.Tensor]
attention_mask: torch.Tensor
# Decoder values
decoder_input_ids: torch.Tensor
decoder_attention_mask: Optional[torch.Tensor]
encoder_last_hidden_state: Optional[torch.Tensor]
# All tokens
all_decoder_input_ids: List[torch.Tensor]
# Seq2SeqLM keeps track of both encoder and decoder attention keys and values
past_key_values: Optional[List[Tuple]]
# Lengths of all generations present in the batch
input_lengths: List[int]
decoder_input_lengths: List[int]
prefix_offsets: List[int]
read_offsets: List[int]
# Generation helpers
next_token_choosers: List[NextTokenChooser]
stopping_criterias: List[StoppingCriteria]
top_n_tokens: List[int]
top_n_tokens_tensor: torch.Tensor
# Metadata used for padding
max_input_length: int
max_decoder_input_length: int
padding_right_offset: int
# Maximum number of tokens this batch will grow to
max_tokens: int
def to_pb(self) -> generate_pb2.CachedBatch:
"""Convert a Seq2SeqLMBatch to a text_generation_server.v1.CachedBatch protobuf"""
return generate_pb2.CachedBatch(
id=self.batch_id,
request_ids=[r.id for r in self.requests],
size=len(self),
max_tokens=self.max_tokens,
)
@classmethod
def from_pb(
cls,
pb: generate_pb2.Batch,
tokenizer: PreTrainedTokenizerBase,
dtype: torch.dtype,
device: torch.device,
) -> "Seq2SeqLMBatch":
"""Convert a text_generation_server.v1.Batch protobuf to a Seq2SeqLMBatch"""
inputs = []
next_token_choosers = []
stopping_criterias = []
top_n_tokens = []
decoder_input_lengths = []
prefix_offsets = []
read_offsets = []
requests_idx_mapping = {}
# Parse batch
max_truncation = 0
padding_right_offset = 0
max_decode_tokens = 0
for i, r in enumerate(pb.requests):
inputs.append(concat_text_chunks(r.input_chunks.chunks))
requests_idx_mapping[r.id] = i
decoder_input_lengths.append(1)
next_token_choosers.append(
NextTokenChooser.from_pb(r.parameters, device, tokenizer)
)
stopping_criteria = StoppingCriteria.from_pb(
r.stopping_parameters, tokenizer
)
stopping_criterias.append(stopping_criteria)
top_n_tokens.append(r.top_n_tokens)
max_truncation = max(max_truncation, r.truncate)
max_decode_tokens += stopping_criteria.max_new_tokens
padding_right_offset = max(
padding_right_offset, stopping_criteria.max_new_tokens
)
# Tokenize batch
tokenized_inputs = tokenizer(
inputs,
return_tensors="pt",
padding=True,
return_token_type_ids=False,
truncation=True,
max_length=max_truncation,
).to(device)
input_lengths = tokenized_inputs["attention_mask"].sum(1)
max_input_length = input_lengths.max()
# Decoder sequence only contains the bos_token
decoder_input_ids = (
torch.tensor(tokenizer.bos_token_id, device=device)
.repeat(len(pb.requests))
.view(-1, 1)
)
for _ in pb.requests:
prefix_offsets.append(0)
read_offsets.append(1)
all_decoder_input_ids = decoder_input_ids.view(-1).split(1)
top_n_tokens_tensor = torch.tensor(
top_n_tokens, device=device, dtype=torch.int64
)
max_tokens = len(inputs) * (max_input_length + max_decode_tokens)
return cls(
batch_id=pb.id,
requests=pb.requests,
requests_idx_mapping=requests_idx_mapping,
input_ids=tokenized_inputs["input_ids"],
attention_mask=tokenized_inputs["attention_mask"],
decoder_input_ids=decoder_input_ids,
all_decoder_input_ids=list(all_decoder_input_ids),
decoder_attention_mask=None,
encoder_last_hidden_state=None,
past_key_values=None,
input_lengths=input_lengths.tolist(),
decoder_input_lengths=decoder_input_lengths,
prefix_offsets=prefix_offsets,
read_offsets=read_offsets,
next_token_choosers=next_token_choosers,
stopping_criterias=stopping_criterias,
top_n_tokens=top_n_tokens,
top_n_tokens_tensor=top_n_tokens_tensor,
max_input_length=max_input_length.item(),
max_decoder_input_length=1,
padding_right_offset=padding_right_offset,
max_tokens=max_tokens,
)
@tracer.start_as_current_span("filter")
def filter(self, request_ids: List[int]) -> Optional["Seq2SeqLMBatch"]:
if len(request_ids) == 0:
raise ValueError("Batch must have at least one request")
if len(request_ids) == len(self):
return self
keep_indices = []
# New values after filtering
requests_idx_mapping = {}
requests = []
input_lengths = []
decoder_input_lengths = []
prefix_offsets = []
read_offsets = []
all_decoder_input_ids = []
next_token_choosers = []
stopping_criterias = []
top_n_tokens = []
max_input_length = 0
max_decoder_input_length = 0
padding_right_offset = 0
total_remaining_decode_tokens = 0
for i, request_id in enumerate(request_ids):
idx = self.requests_idx_mapping[request_id]
requests_idx_mapping[request_id] = i
keep_indices.append(idx)
requests.append(self.requests[idx])
prefix_offsets.append(self.prefix_offsets[idx])
read_offsets.append(self.read_offsets[idx])
all_decoder_input_ids.append(self.all_decoder_input_ids[idx])
request_input_length = self.input_lengths[idx]
input_lengths.append(request_input_length)
max_input_length = max(max_input_length, request_input_length)
request_decoder_input_length = self.decoder_input_lengths[idx]
decoder_input_lengths.append(request_decoder_input_length)
max_decoder_input_length = max(
max_decoder_input_length, request_decoder_input_length
)
next_token_choosers.append(self.next_token_choosers[idx])
stopping_criteria = self.stopping_criterias[idx]
stopping_criterias.append(stopping_criteria)
top_n_tokens.append(self.top_n_tokens[idx])
remaining_decode_tokens = (
stopping_criteria.max_new_tokens - stopping_criteria.current_tokens
)
total_remaining_decode_tokens += remaining_decode_tokens
padding_right_offset = max(padding_right_offset, remaining_decode_tokens)
# Apply indices to input_ids, attention mask, past key values and other items that need to be cached
self.decoder_input_ids = self.decoder_input_ids[keep_indices]
self.attention_mask = self.attention_mask[keep_indices, -max_input_length:]
if self.decoder_attention_mask is not None:
self.decoder_attention_mask = self.decoder_attention_mask[
keep_indices,
-(self.padding_right_offset + max_decoder_input_length) : (
self.decoder_attention_mask.shape[1] - self.padding_right_offset
)
+ padding_right_offset,
]
self.encoder_last_hidden_state = self.encoder_last_hidden_state[
keep_indices, -max_input_length:
]
# Ensure that past_key_values tensors can be updated in-place
if type(self.past_key_values[0]) == tuple:
self.past_key_values = [
[t for t in layer] for layer in self.past_key_values
]
decoder_past_seq_len = max_decoder_input_length - 1
for layer in self.past_key_values:
layer[0] = layer[0][keep_indices, :, -decoder_past_seq_len:]
layer[1] = layer[1][keep_indices, :, -decoder_past_seq_len:]
layer[2] = layer[2][keep_indices, :, -max_input_length:]
layer[3] = layer[3][keep_indices, :, -max_input_length:]
top_n_tokens_tensor = self.top_n_tokens_tensor[keep_indices]
max_tokens = (
len(request_ids) * (max_input_length + max_decoder_input_length)
+ remaining_decode_tokens
)
self.requests = requests
self.requests_idx_mapping = requests_idx_mapping
self.input_ids = None
self.all_decoder_input_ids = all_decoder_input_ids
self.input_lengths = input_lengths
self.decoder_input_lengths = decoder_input_lengths
self.prefix_offsets = prefix_offsets
self.read_offsets = read_offsets
self.next_token_choosers = next_token_choosers
self.stopping_criterias = stopping_criterias
self.top_n_tokens = top_n_tokens
self.top_n_tokens_tensor = top_n_tokens_tensor
self.max_input_length = max_input_length
self.max_decoder_input_length = max_decoder_input_length
self.padding_right_offset = padding_right_offset
self.max_tokens = max_tokens
return self
@classmethod
@tracer.start_as_current_span("concatenate")
def concatenate(cls, batches: List["Seq2SeqLMBatch"]) -> "Seq2SeqLMBatch":
"""Concatenate multiple batches together by padding internal torch tensors"""
# Used for padding
total_batch_size = 0
max_input_length = 0
max_decoder_input_length = 0
padding_right_offset = 0
for batch in batches:
total_batch_size += len(batch)
max_input_length = max(max_input_length, batch.max_input_length)
max_decoder_input_length = max(
max_decoder_input_length, batch.max_decoder_input_length
)
padding_right_offset = max(padding_right_offset, batch.padding_right_offset)
# Batch attributes
requests = []
requests_idx_mapping = {}
all_decoder_input_ids = []
input_lengths = []
decoder_input_lengths = []
prefix_offsets = []
read_offsets = []
next_token_choosers = []
stopping_criterias = []
top_n_tokens = []
max_tokens = 0
# Batch tensors
attention_mask = None
decoder_input_ids = None
decoder_attention_mask = None
encoder_last_hidden_state = None
top_n_tokens_tensor = None
past_key_values = []
# Used for slicing correctly inside the tensors
# Equivalent to a cumsum on batch sizes
start_index = 0
for i, batch in enumerate(batches):
# Extend all list attributes
requests.extend(batch.requests)
all_decoder_input_ids.extend(batch.all_decoder_input_ids)
input_lengths.extend(batch.input_lengths)
decoder_input_lengths.extend(batch.decoder_input_lengths)
prefix_offsets.extend(batch.prefix_offsets)
read_offsets.extend(batch.read_offsets)
next_token_choosers.extend(batch.next_token_choosers)
stopping_criterias.extend(batch.stopping_criterias)
top_n_tokens.extend(batch.top_n_tokens)
if i == 0:
requests_idx_mapping = batch.requests_idx_mapping
else:
# We need to offset the mapping for each batch by the cumulative batch size
for k, v in batch.requests_idx_mapping.items():
requests_idx_mapping[k] = v + start_index
# Slicing end index for this batch
end_index = start_index + len(batch)
# We only concatenate batches that did at least one step
if batch.encoder_last_hidden_state is None:
raise ValueError("Batch encoder_last_hidden_state cannot be None")
# Create padded tensor
if attention_mask is None:
attention_mask = batch.attention_mask.new_zeros(
(total_batch_size, max_input_length),
)
# Copy to correct indices
attention_mask[start_index:end_index, -batch.max_input_length :] = (
batch.attention_mask[:, -batch.max_input_length :]
)
# Create padded tensor
if decoder_input_ids is None:
decoder_input_ids = batch.decoder_input_ids.new_zeros(
(total_batch_size, 1),
)
# Copy to correct indices
decoder_input_ids[start_index:end_index] = batch.decoder_input_ids
# Create padded tensor
if decoder_attention_mask is None:
# As decoder_attention_mask might not exist, we use `batch.attention_mask` for device here
decoder_attention_mask = batch.attention_mask.new_zeros(
(total_batch_size, max_decoder_input_length + padding_right_offset),
)
# If the decoder mask does not exist yet, all generations started at the same time and we never concatenated
# this batch. All generations are of length `batch.max_decoder_input_length`.
left_offset = max_decoder_input_length - batch.max_decoder_input_length
if batch.decoder_attention_mask is None:
decoder_attention_mask[
start_index:end_index,
left_offset:-padding_right_offset,
] = 1
# If it exists, we need to index
else:
batch_left_offset = (
batch.decoder_attention_mask.shape[1]
- batch.max_decoder_input_length
- batch.padding_right_offset
)
decoder_attention_mask[
start_index:end_index,
left_offset:-padding_right_offset,
] = batch.decoder_attention_mask[
:,
batch_left_offset : -batch.padding_right_offset,
]
# Create padded tensor
if encoder_last_hidden_state is None:
encoder_last_hidden_state = batch.encoder_last_hidden_state.new_zeros(
(
total_batch_size,
max_input_length,
batch.encoder_last_hidden_state.shape[-1],
),
)
if top_n_tokens_tensor is None:
top_n_tokens_tensor = batches[0].top_n_tokens_tensor.new_zeros(
total_batch_size,
)
top_n_tokens_tensor[start_index:end_index] = batch.top_n_tokens_tensor
# Copy to correct indices
encoder_last_hidden_state[
start_index:end_index, -batch.max_input_length :, :
] = batch.encoder_last_hidden_state[:, -batch.max_input_length :, :]
batch.encoder_last_hidden_state = None
# Ensure that we can update tensors in-place
if type(batch.past_key_values[0]) == tuple:
batch.past_key_values = [
[t for t in layer] for layer in batch.past_key_values
]
# Add eventual padding tokens that were added while concatenating
max_tokens += batch.max_tokens + (
max_input_length
- batch.max_input_length
+ max_decoder_input_length
- batch.max_decoder_input_length
) * len(batch)
start_index = end_index
# Determine shapes for new past kv tensors
first_past_kvs = batches[0].past_key_values
_, num_heads, _, head_dim = first_past_kvs[0][0].shape
padded_dec_t_shape = (
total_batch_size,
num_heads,
(max_decoder_input_length - 1),
head_dim,
)
padded_enc_t_shape = (
total_batch_size,
num_heads,
max_input_length,
head_dim,
)
# Iterate over attention layers
for j in range(len(first_past_kvs)):
past_key_values.append([])
# Decoder past
for k in range(0, 2):
# Initialize tensors
padded_past_values = first_past_kvs[j][k].new_zeros(padded_dec_t_shape)
past_key_values[j].append(padded_past_values)
start_index = 0
for batch in batches:
t = batch.past_key_values[j][k]
# Clear reference to the original tensor
batch.past_key_values[j][k] = None
# Slicing end index for this batch
end_index = start_index + len(batch)
# We slice the past keys and values to remove the padding from previous batches
past_seq_len = batch.max_decoder_input_length - 1
padded_past_values[start_index:end_index, :, -past_seq_len:, :] = t[
:, :, -past_seq_len:, :
]
del t
start_index = end_index
# Encoder past
for k in range(2, 4):
# Initialize tensors
padded_past_values = first_past_kvs[j][k].new_zeros(padded_enc_t_shape)
past_key_values[j].append(padded_past_values)
start_index = 0
for batch in batches:
t = batch.past_key_values[j][k]
# Clear reference to the original tensor
batch.past_key_values[j][k] = None
# Slicing end index for this batch
end_index = start_index + len(batch)
# We slice the past keys and values to remove the padding from previous batches
padded_past_values[
start_index:end_index, :, -batch.max_input_length :, :
] = t[:, :, -batch.max_input_length :, :]
del t
start_index = end_index
return cls(
batch_id=batches[0].batch_id,
requests=requests,
requests_idx_mapping=requests_idx_mapping,
input_ids=None,
attention_mask=attention_mask,
decoder_input_ids=decoder_input_ids,
all_decoder_input_ids=all_decoder_input_ids,
decoder_attention_mask=decoder_attention_mask,
encoder_last_hidden_state=encoder_last_hidden_state,
past_key_values=past_key_values,
input_lengths=input_lengths,
decoder_input_lengths=decoder_input_lengths,
prefix_offsets=prefix_offsets,
read_offsets=read_offsets,
next_token_choosers=next_token_choosers,
stopping_criterias=stopping_criterias,
top_n_tokens=top_n_tokens,
top_n_tokens_tensor=top_n_tokens_tensor,
max_input_length=max_input_length,
max_decoder_input_length=max_decoder_input_length,
padding_right_offset=padding_right_offset,
max_tokens=max_tokens,
)
def __len__(self):
return len(self.requests)
class Seq2SeqLM(Model):
def __init__(
self,
model_id: str,
revision: Optional[str] = None,
quantize: Optional[str] = None,
speculator: Optional[str] = None,
dtype: Optional[torch.dtype] = None,
trust_remote_code: bool = False,
):
if speculator:
raise RuntimeError("Speculator decoding is not enabled for AutoModel")
if torch.cuda.is_available():
device = torch.device("cuda")
dtype = torch.float16 if dtype is None else dtype
else:
if quantize:
raise ValueError("quantization is not available on CPU")
device = torch.device("cpu")
dtype = torch.float32 if dtype is None else dtype
model = AutoModelForSeq2SeqLM.from_pretrained(
model_id,
revision=revision,
torch_dtype=dtype,
device_map=(
"auto"
if torch.cuda.is_available() and torch.cuda.device_count() > 1
else None
),
load_in_8bit=quantize == "bitsandbytes",
trust_remote_code=trust_remote_code,
)
if torch.cuda.is_available() and torch.cuda.device_count() == 1:
model = model.cuda()
tokenizer = AutoTokenizer.from_pretrained(
model_id,
revision=revision,
padding_side="left",
truncation_side="left",
trust_remote_code=trust_remote_code,
)
tokenizer.bos_token_id = model.config.decoder_start_token_id
super(Seq2SeqLM, self).__init__(
model=model,
tokenizer=tokenizer,
requires_padding=True,
dtype=dtype,
device=device,
)
@property
def batch_type(self) -> Type[Seq2SeqLMBatch]:
return Seq2SeqLMBatch
def decode(self, decoder_ids: List[int]) -> str:
return self.tokenizer.decode(
decoder_ids, skip_special_tokens=True, clean_up_tokenization_spaces=False
)
def forward(
self,
input_ids,
attention_mask,
decoder_input_ids,
decoder_attention_mask: Optional,
encoder_last_hidden_state: Optional,
past_key_values: Optional = None,
) -> Tuple[
torch.Tensor,
Optional[torch.Tensor],
torch.Tensor,
List[Tuple[torch.Tensor, torch.Tensor, torch.Tensor, torch.Tensor]],
]:
# Model Forward
outputs = self.model.forward(
input_ids=input_ids,
attention_mask=attention_mask,
decoder_input_ids=decoder_input_ids,
decoder_attention_mask=decoder_attention_mask,
encoder_outputs=encoder_last_hidden_state,
past_key_values=past_key_values,
use_cache=True,
)
if isinstance(outputs, tuple):
# Our custom models
outputs, speculative_logits = outputs
else:
# Generic transformers models
speculative_logits = None
return (
outputs.logits,
speculative_logits,
outputs.encoder_last_hidden_state,
outputs.past_key_values,
)
@tracer.start_as_current_span("generate_token")
def generate_token(
self, batch: Seq2SeqLMBatch
) -> Tuple[List[Generation], Optional[Seq2SeqLMBatch], Tuple[int, int]]:
start = time.time_ns()
if batch.decoder_attention_mask is not None:
# slice to the correct shape
decoder_attention_mask = batch.decoder_attention_mask[
:, : -batch.padding_right_offset
]
else:
decoder_attention_mask = None
# Wrap `encoder_last_hidden_state` because for some reason, Transformers does a `encoder_last_hidden_state[0]`
# internally...
if batch.encoder_last_hidden_state is not None:
encoder_last_hidden_state = [batch.encoder_last_hidden_state]
else:
encoder_last_hidden_state = None
logits, speculative_logits, encoder_last_hidden_state, past = self.forward(
batch.input_ids,
batch.attention_mask,
batch.decoder_input_ids,
decoder_attention_mask,
encoder_last_hidden_state,
batch.past_key_values,
)
# Speculation is not active for seq2seq
accepted_ids = torch.ones_like(batch.decoder_input_ids)[:, 0]
batch_top_token_ids, batch_top_token_logprobs = batch_top_tokens(
batch.top_n_tokens,
batch.top_n_tokens_tensor,
torch.log_softmax(logits[:, -1], -1),
accepted_ids,
)
start_decode = time.time_ns()
# Finished requests
generations: List[Generation] = []
stopped = True
# Zipped iterator
iterator = zip(
batch.requests,
batch.input_lengths,
batch.prefix_offsets,
batch.read_offsets,
batch.decoder_input_lengths,
logits,
batch.next_token_choosers,
batch.stopping_criterias,
batch.all_decoder_input_ids,
batch.top_n_tokens,
batch_top_token_ids,
batch_top_token_logprobs,
)
# For each member of the batch
for i, (
request,
input_length,
prefix_offset,
read_offset,
decoder_input_length,
logits,
next_token_chooser,
stopping_criteria,
all_decoder_input_ids,
top_n_tokens,
top_token_ids,
top_token_logprobs,
) in enumerate(iterator):
# Select next token
next_token_id, logprobs = next_token_chooser(
all_decoder_input_ids.view(1, -1), logits[-1:, :]
)
# Append next token to decoder tokens
all_decoder_input_ids = torch.cat(
[all_decoder_input_ids, next_token_id.squeeze(1)]
)
new_decoder_input_length = decoder_input_length + 1
# Generated token
next_token_logprob = logprobs[-1, next_token_id]
next_token_id_squeezed = next_token_id.squeeze()
next_token_text, prefix_offset, read_offset = self.decode_token(
all_decoder_input_ids, prefix_offset, read_offset
)
# Evaluate stopping criteria
stop, reason = stopping_criteria(next_token_id, next_token_text)
if not stop:
stopped = False
# Shard generations
# All generations will be appended in the rust sharded client
if i % self.world_size == self.rank:
if stop:
# Slice with decoder_input_length to remove padding
# Decode all tokens
output_text, _, _ = self.decode_token(
all_decoder_input_ids,
prefix_offset=len(all_decoder_input_ids)
- decoder_input_length
- 1,
read_offset=len(all_decoder_input_ids) - decoder_input_length,
skip_special_tokens=True,
)
# Get seed
if isinstance(next_token_chooser.choice, Sampling):
seed = next_token_chooser.choice.seed
else:
seed = None
generated_text = GeneratedText(
output_text, stopping_criteria.current_tokens, reason, seed
)
else:
generated_text = None
# Prefill
if stopping_criteria.current_tokens == 1 and request.prefill_logprobs:
prefill_tokens = Tokens(
[self.tokenizer.bos_token_id],
[float("nan")],
[self.tokenizer.bos_token],
[False],
)
else:
prefill_tokens = None
if top_n_tokens > 0:
all_top_tokens = []
for top_token_ids, top_token_logprobs in zip(
top_token_ids, top_token_logprobs
):
toptoken_texts = self.tokenizer.batch_decode(
top_token_ids,
clean_up_tokenization_spaces=False,
skip_special_tokens=False,
)
special_toptokens = [
token_id in self.all_special_ids
for token_id in top_token_ids
]
top_tokens = Tokens(
top_token_ids,
top_token_logprobs,
toptoken_texts,
special_toptokens,
)
all_top_tokens.append(top_tokens)
top_tokens = all_top_tokens
else:
top_tokens = None
generation = Generation(
request.id,
prefill_tokens,
Tokens(
[next_token_id_squeezed],
[next_token_logprob],
[next_token_text],
[next_token_id_squeezed.item() in self.all_special_ids],
),
generated_text,
top_tokens,
)
generations.append(generation)
# Update values
batch.next_token_choosers[i] = batch.next_token_choosers[i].advance_grammar(
next_token_id_squeezed.item()
)
batch.decoder_input_ids[i] = next_token_id
batch.all_decoder_input_ids[i] = all_decoder_input_ids
batch.input_lengths[i] = input_length
batch.decoder_input_lengths[i] = new_decoder_input_length
batch.prefix_offsets[i] = prefix_offset
batch.read_offsets[i] = read_offset
batch.max_input_length = max(batch.max_input_length, input_length)
batch.max_decoder_input_length = max(
batch.max_decoder_input_length, new_decoder_input_length
)
# We finished all generations in the batch; there is no next batch
if stopped:
forward_ns = start_decode - start
decode_ns = time.time_ns() - start_decode
return generations, None, (forward_ns, decode_ns)
# We don't need input_ids after the prefill forward
batch.input_ids = None
batch.encoder_last_hidden_state = encoder_last_hidden_state
batch.past_key_values = past
# Update decoder_attention_mask as we added a new token to input_ids
if batch.decoder_attention_mask is not None:
batch.decoder_attention_mask[:, -batch.padding_right_offset] = 1
batch.padding_right_offset -= 1
forward_ns = start_decode - start
decode_ns = time.time_ns() - start_decode
return generations, batch, (forward_ns, decode_ns)