def _check_grad_norms(self, grad_norm):
"""Check that grad norms are consistent across workers."""
if self._grad_norm_buf is not None:
self._grad_norm_buf.zero_()
self._grad_norm_buf[self.data_parallel_rank] = grad_norm
distributed_utils.all_reduce(
self._grad_norm_buf, group=self.data_parallel_process_group
)
def is_consistent(tensor):
max_abs_diff = torch.max(torch.abs(tensor - tensor[0]))
return (
torch.isfinite(tensor).all()
or (max_abs_diff / (tensor[0] + 1e-6) < 1e-6).all()
)
if not is_consistent(self._grad_norm_buf):
pretty_detail = "\n".join(
"rank {:3d} = {:.8f}".format(r, n)
for r, n in enumerate(self._grad_norm_buf.tolist())
)
error_detail = "grad_norm across the workers:\n{}\n".format(
pretty_detail
)
# use FloatingPointError to trigger NanDetector
raise FloatingPointError(
"Fatal error: gradients are inconsistent between workers. "
"Try --ddp-backend=legacy_ddp. "
"Or are you mixing up different generation of GPUs in training?"
+ "\n"
+ "-" * 80
+ "\n{}\n".format(error_detail)
+ "-" * 80
)
def _sync_sample_ratios(self, ratios):
# in case the ratios are not precisely the same across processes
# also to ensure every procresses update the ratios in the same pace
ratios = torch.DoubleTensor(ratios)
if torch.distributed.is_initialized():
if torch.cuda.is_available():
distributed_utils.all_reduce(
ratios.cuda(),
group=distributed_utils.get_data_parallel_group())
else:
distributed_utils.all_reduce(
ratios, group=distributed_utils.get_data_parallel_group())
ret = ratios.cpu()
ret = ret.numpy()
return ret
def all_reduce_params(params):
buffer = self.buffer
nonzero_buffer = False
if len(params) > 1:
offset = 0
for p in params:
sz = p.numel()
if p.grad is not None:
buffer[offset : offset + sz].copy_(p.grad.data.view(-1))
nonzero_buffer = True
else:
buffer[offset : offset + sz].zero_()
offset += sz
else:
# we only have a single grad to all-reduce
p = params[0]
if p.grad is not None:
buffer = p.grad.data
nonzero_buffer = True
elif p.numel() <= self.buffer.numel():
buffer = buffer[: p.numel()]
buffer.zero_()
else:
buffer = torch.zeros_like(p)
if nonzero_buffer:
buffer.div_(self.world_size)
utils.all_reduce(buffer, self.process_group)
# copy all-reduced grads back into their original place
offset = 0
for p in params:
sz = p.numel()
if p.grad is not None:
p.grad.data.copy_(buffer[offset : offset + sz].view_as(p))
else:
p.grad = buffer[offset : offset + sz].view_as(p).clone()
offset += sz
def _aggregate_model_parallel_grad_norm(total_norm):
total_norm = total_norm**2
distributed_utils.all_reduce(
total_norm, group=distributed_utils.get_model_parallel_group())
total_norm = total_norm**0.5
return total_norm
