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distributed=n_gpu > 1) |
meta_loader = PrefetchLoader(meta_loader) |
# Prepare model |
if opts.checkpoint: |
checkpoint = torch.load(opts.checkpoint) |
else: |
checkpoint = {} |
model = UniterForPretrainingForVCR.from_pretrained( |
opts.model_config, checkpoint, |
img_dim=IMG_DIM, img_label_dim=IMG_LABEL_DIM) |
model.init_type_embedding() |
model.init_word_embedding(NUM_SPECIAL_TOKENS) |
model.to(device) |
model.train() |
# make sure every process has same model parameters in the beginning |
broadcast_tensors([p.data for p in model.parameters()], 0) |
set_dropout(model, opts.dropout) |
# Prepare optimizer |
optimizer = build_optimizer(model, opts) |
task2scaler = {t: i for i, t in enumerate(train_dataloaders.keys())} |
model, optimizer = amp.initialize(model, optimizer, |
num_losses=len(task2scaler), |
enabled=opts.fp16, opt_level='O2') |
global_step = 0 |
LOGGER.info(f"***** Running training with {n_gpu} GPUs *****") |
LOGGER.info(" Batch size = %d", opts.train_batch_size) |
LOGGER.info(" Accumulate steps = %d", opts.gradient_accumulation_steps) |
LOGGER.info(" Num steps = %d", opts.num_train_steps) |
# to compute training statistics |
task2loss = {task: RunningMeter(f'loss/{task}') |
for task in train_dataloaders.keys()} |
n_examples = defaultdict(int) |
n_in_units = defaultdict(int) |
n_loss_units = defaultdict(int) |
grad_norm = 0 |
start = time() |
# quick hack for amp delay_unscale bug |
optimizer.zero_grad() |
optimizer.step() |
for step, (name, batch) in enumerate(meta_loader): |
# forward pass |
n_examples[name] += batch['input_ids'].size(0) |
n_in_units[name] += (batch['attn_masks'] == 1).sum().item() |
task = name.split('_')[0] |
loss = model(batch, task=task, compute_loss=True) |
n_loss_units[name] += loss.size(0) |
loss = loss.mean() # loss is not normalized in model |
# backward pass |
delay_unscale = (step+1) % opts.gradient_accumulation_steps != 0 |
with amp.scale_loss(loss, optimizer, delay_unscale=delay_unscale, |
loss_id=task2scaler[name]) as scaled_loss: |
scaled_loss.backward() |
if not delay_unscale: |
# gather gradients from every processes |
# do this before unscaling to make sure every process uses |
# the same gradient scale |
grads = [p.grad.data for p in model.parameters() |
if p.requires_grad and p.grad is not None] |
all_reduce_and_rescale_tensors(grads, float(1)) |
task2loss[name](loss.item()) |
# optimizer update and logging |
if (step + 1) % opts.gradient_accumulation_steps == 0: |
global_step += 1 |
# learning rate scheduling |
lr_this_step = get_lr_sched(global_step, opts) |
for param_group in optimizer.param_groups: |
param_group['lr'] = lr_this_step |
TB_LOGGER.add_scalar('lr', lr_this_step, global_step) |
# log loss |
# NOTE: not gathered across GPUs for efficiency |
TB_LOGGER.log_scaler_dict({ll.name: ll.val |
for ll in task2loss.values() |
if ll.val is not None}) |
TB_LOGGER.step() |
# update model params |
if opts.grad_norm != -1: |
grad_norm = clip_grad_norm_(amp.master_params(optimizer), |
opts.grad_norm) |
TB_LOGGER.add_scalar('grad_norm', grad_norm, global_step) |
optimizer.step() |
optimizer.zero_grad() |
pbar.update(1) |
if global_step % 100 == 0: |
# monitor training throughput |
LOGGER.info(f'==============Step {global_step}===============') |
for t in train_dataloaders.keys(): |
assert all(tt == t for tt in all_gather_list(t)) |
tot_ex = sum(all_gather_list(n_examples[t])) |
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