chore: import upstream snapshot with attribution
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from .glat_loss import *
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# Copyright (c) Facebook, Inc. and its affiliates.
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#
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# This source code is licensed under the MIT license found in the
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# LICENSE file in the root directory of this source tree.
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import math
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from math import log
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import torch
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import torch.nn.functional as F
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from fairseq import metrics, utils
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from fairseq.criterions import FairseqCriterion, register_criterion
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from torch import Tensor
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import numpy as np
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@register_criterion("glat_loss")
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class LabelSmoothedDualImitationCriterion(FairseqCriterion):
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def __init__(self, task, label_smoothing):
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super().__init__(task)
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self.label_smoothing = label_smoothing
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@staticmethod
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def add_args(parser):
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"""Add criterion-specific arguments to the parser."""
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parser.add_argument(
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"--label-smoothing",
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default=0.0,
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type=float,
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metavar="D",
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help="epsilon for label smoothing, 0 means no label smoothing",
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)
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parser.add_argument('--mse-lambda', default=10, type=float, metavar='D')
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def _compute_loss(
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self, outputs, targets, masks=None, label_smoothing=0.0, name="loss", factor=1.0
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):
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"""
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outputs: batch x len x d_model
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targets: batch x len
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masks: batch x len
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policy_logprob: if there is some policy
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depends on the likelihood score as rewards.
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"""
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def mean_ds(x: Tensor, dim=None) -> Tensor:
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return (
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x.float().mean().type_as(x)
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if dim is None
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else x.float().mean(dim).type_as(x)
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)
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if masks is not None:
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outputs, targets = outputs[masks], targets[masks]
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if masks is not None and not masks.any():
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nll_loss = torch.tensor(0)
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loss = nll_loss
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else:
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logits = F.log_softmax(outputs, dim=-1)
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if targets.dim() == 1:
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losses = F.nll_loss(logits, targets.to(logits.device), reduction="none")
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else: # soft-labels
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losses = F.kl_div(logits, targets.to(logits.device), reduction="none")
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losses = losses.sum(-1)
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nll_loss = mean_ds(losses)
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if label_smoothing > 0:
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loss = (
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nll_loss * (1 - label_smoothing) - mean_ds(logits) * label_smoothing
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)
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else:
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loss = nll_loss
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loss = loss * factor
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return {"name": name, "loss": loss, "nll_loss": nll_loss, "factor": factor}
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def _custom_loss(self, loss, name="loss", factor=1.0):
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return {"name": name, "loss": loss, "factor": factor}
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def forward(self, model, sample, reduce=True):
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"""Compute the loss for the given sample.
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Returns a tuple with three elements:
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1) the loss
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2) the sample size, which is used as the denominator for the gradient
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3) logging outputs to display while training
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"""
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nsentences, ntokens = sample["nsentences"], sample["ntokens"]
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# B x T
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src_tokens, src_lengths = (
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sample["net_input"]["src_tokens"],
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sample["net_input"]["src_lengths"],
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)
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tgt_tokens, prev_output_tokens = sample["target"], sample["prev_target"]
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if 'glat' in sample:
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glat = sample['glat']
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else:
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glat = None
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outputs = model(src_tokens, src_lengths, prev_output_tokens, tgt_tokens, glat)
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losses, nll_loss = [], []
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for obj in outputs:
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if obj.startswith('glat'):
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continue
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if outputs[obj].get("loss", None) is None:
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_losses = self._compute_loss(
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outputs[obj].get("out"),
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outputs[obj].get("tgt"),
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outputs[obj].get("mask", None),
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outputs[obj].get("ls", 0.0),
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name=obj + "-loss",
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factor=outputs[obj].get("factor", 1.0),
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)
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else:
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_losses = self._custom_loss(
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outputs[obj].get("loss"),
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name=obj + "-loss",
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factor=outputs[obj].get("factor", 1.0),
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)
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losses += [_losses]
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if outputs[obj].get("nll_loss", False):
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nll_loss += [_losses.get("nll_loss", 0.0)]
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loss = sum(l["loss"] for l in losses)
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nll_loss = sum(l for l in nll_loss) if len(nll_loss) > 0 else loss.new_tensor(0)
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# NOTE:
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# we don't need to use sample_size as denominator for the gradient
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# here sample_size is just used for logging
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sample_size = 1
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logging_output = {
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"loss": loss.data,
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"nll_loss": nll_loss.data,
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"ntokens": ntokens,
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"nsentences": nsentences,
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"sample_size": sample_size,
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}
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if "glat_accu" in outputs:
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logging_output["glat_accu"] = outputs['glat_accu']
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if "glat_context_p" in outputs:
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logging_output['glat_context_p'] = outputs['glat_context_p']
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for l in losses:
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logging_output[l["name"]] = (
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utils.item(l["loss"].data / l["factor"])
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if reduce
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else l[["loss"]].data / l["factor"]
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)
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return loss, sample_size, logging_output
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@staticmethod
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def reduce_metrics(logging_outputs) -> None:
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"""Aggregate logging outputs from data parallel training."""
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sample_size = utils.item(
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sum(log.get("sample_size", 0) for log in logging_outputs)
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)
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loss = utils.item(sum(log.get("loss", 0) for log in logging_outputs))
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nll_loss = utils.item(sum(log.get("nll_loss", 0) for log in logging_outputs))
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metrics.log_scalar(
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"loss", loss / sample_size / math.log(2), sample_size, round=3
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)
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metrics.log_scalar(
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"nll_loss", nll_loss / sample_size / math.log(2), sample_size, round=3
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)
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metrics.log_derived(
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"ppl", lambda meters: utils.get_perplexity(meters["loss"].avg)
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)
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log_metric("glat_accu", logging_outputs)
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log_metric("glat_context_p", logging_outputs)
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for key in logging_outputs[0]:
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if key[-5:] == "-loss":
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val = sum(log.get(key, 0) for log in logging_outputs)
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metrics.log_scalar(
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key[:-5],
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val / sample_size / math.log(2) if sample_size > 0 else 0.0,
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sample_size,
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round=3,
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)
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@staticmethod
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def logging_outputs_can_be_summed() -> bool:
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"""
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Whether the logging outputs returned by `forward` can be summed
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across workers prior to calling `reduce_metrics`. Setting this
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to True will improves distributed training speed.
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"""
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return False
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def log_metric(key, logging_outputs):
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if len(logging_outputs) > 0 and key in logging_outputs[0]:
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metrics.log_scalar(
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key, utils.item(np.mean([log.get(key, 0) for log in logging_outputs])), priority=10, round=3
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)
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