def train(epoch, tokenizer, model, device, loader, optimizer):
"""
用于训练的方法
Function to be called for training with the parameters passed from main function
"""
model.train()
time1=time.time()
for _, data in enumerate(loader, 0):
y = data["target_ids"].to(device, dtype=torch.long)
y_ids = y[:, :-1].contiguous() # target, from start to end(except end of token, <EOS>). e.g. "你好吗？"
lm_labels = y[:, 1:].clone().detach() # target, for second to end.e.g."好吗？<EOS>"
lm_labels[y[:, 1:] == tokenizer.pad_token_id] = -100 # releted to pad_token and loss. for detail, check here: https://github.com/Shivanandroy/T5-Finetuning-PyTorch/issues/3
ids = data["source_ids"].to(device, dtype=torch.long) # input. e.g. "how are you?"
mask = data["source_mask"].to(device, dtype=torch.long)
outputs = model(
input_ids=ids,
attention_mask=mask,
decoder_input_ids=y_ids,
labels=lm_labels,
)
loss = outputs[0]
# 每100步打印日志
if _ % 100 == 0 and _!=0:
time2=time.time()
print(_,"epoch:"+str(epoch)+"-loss:"+str(loss)+";each step's time spent:"+str(float(time2-time1)/float(_+0.0001)))
# training_logger.add_row(str(epoch), str(_), str(loss))
# console.print(training_logger)
optimizer.zero_grad()
loss.backward()
optimizer.step()
if labels is not None and decoder_input_ids is None and decoder_inputs_embeds is None:
# get decoder inputs from shifting lm labels to the right
decoder_input_ids = self._shift_right(labels)
why don't y_ids and lm_labels have a start_token like
<s>May this affect decode during the testing phase？
this is the official code in T5ForConditionalGeneration; i think we should only pass labels like
你好吗？<EOS>, then the code below will do shift.