hf_text-generation-inference/server/text_generation_server/models/t5.py

import torch
import torch.distributed

from typing import List, Optional, Tuple

from accelerate import init_empty_weights
from safetensors import safe_open
from transformers import (
    AutoTokenizer,
    AutoModelForSeq2SeqLM,
    AutoConfig,
)

from text_generation_server.models import Seq2SeqLM
from text_generation_server.utils import (
    initialize_torch_distributed,
    weight_files,
)
from transformers.models.t5.parallel_layers import (
    TensorParallelRowLinear,
    TensorParallelColumnLinear,
    TensorParallelEmbedding,
)

HAS_BITS_AND_BYTES = True
try:
    import bitsandbytes as bnb
    from bitsandbytes.nn import Int8Params
except ImportError as e:
    HAS_BITS_AND_BYTES = False


class T5Sharded(Seq2SeqLM):
    def __init__(
        self,
        model_id: str,
        revision: Optional[str] = None,
        quantize: Optional[str] = None,
    ):
        self.process_group, rank, world_size = initialize_torch_distributed()
        if torch.cuda.is_available():
            device = torch.device(f"cuda:{rank}")
            dtype = torch.float16
        else:
            device = torch.device("cpu")
            dtype = torch.float32

        tokenizer = AutoTokenizer.from_pretrained(
            model_id, revision=revision, padding_side="left", truncation_side="left"
        )

        config = AutoConfig.from_pretrained(
            model_id, revision=revision, tp_parallel=True
        )
        tokenizer.bos_token_id = config.decoder_start_token_id

        torch.distributed.barrier(group=self.process_group)
        filenames = weight_files(model_id, revision=revision, extension=".safetensors")

        with init_empty_weights():
            model = AutoModelForSeq2SeqLM.from_config(config)

        torch.distributed.barrier(group=self.process_group)
        self.load_weights(
            model,
            filenames,
            quantize=quantize,
            device=device,
            dtype=dtype,
            rank=rank,
            world_size=world_size,
        )
        torch.distributed.barrier(group=self.process_group)
        super(Seq2SeqLM, self).__init__(
            model=model,
            tokenizer=tokenizer,
            requires_padding=True,
            dtype=dtype,
            device=device,
            rank=rank,
            world_size=world_size,
        )

    @staticmethod
    def load_weights(
        model,
        filenames: List[str],
        quantize: Optional[str],
        device: torch.device,
        dtype: torch.dtype,
        rank: int,
        world_size: int,
    ):
        parameters = dict(model.named_parameters())
        for file in filenames:
            with safe_open(
                file, framework="pt", device=str(device) if quantize is None else "cpu"
            ) as f:
                for name in f.keys():
                    module_name, param_name = name.rsplit(".", 1)
                    module = model.get_submodule(module_name)

                    current_parameter_tensor = parameters.get(name, None)

                    slice_ = f.get_slice(name)

                    if isinstance(module, TensorParallelColumnLinear):
                        size = slice_.get_shape()[0]
                        block_size = size // world_size
                        start = rank * block_size
                        stop = (rank + 1) * block_size
                        tensor = slice_[start:stop]
                    elif isinstance(module, TensorParallelRowLinear):
                        if param_name == "weight":
                            size = slice_.get_shape()[1]
                            block_size = size // world_size
                            start = rank * block_size
                            stop = (rank + 1) * block_size
                            tensor = slice_[:, start:stop]
                        else:
                            tensor = slice_[:]
                            # XXX: Hack for Rowlinear to add the bias only once.
                            if rank != 0:
                                tensor = torch.zeros_like(tensor)
                    elif isinstance(module, TensorParallelEmbedding):
                        size = slice_.get_shape()[0]
                        block_size = size // world_size
                        start = rank * block_size
                        stop = (rank + 1) * block_size
                        tensor = slice_[start:stop]
                    elif name == "lm_head.weight":
                        size = slice_.get_shape()[0]
                        block_size = size // world_size
                        start = rank * block_size
                        stop = (rank + 1) * block_size
                        tensor = slice_[start:stop]
                    elif "relative_attention_bias.weight" in name:
                        size = slice_.get_shape()[1]
                        block_size = size // world_size
                        start = rank * block_size
                        stop = (rank + 1) * block_size
                        tensor = slice_[:, start:stop]
                    else:
                        try:
                            tensor = slice_[:]
                        except:
                            tensor = f.get_tensor(name)

                    if (
                        current_parameter_tensor is not None
                        and current_parameter_tensor.shape != tensor.shape
                    ):
                        raise ValueError(
                            f"Name {name} -- Current {current_parameter_tensor.shape} and got {tensor.shape}"
                        )

                    tensor = tensor.contiguous()

                    # See: https://github.com/huggingface/transformers/blob/1fe1e3caa44617047f149bcc0c0b566343b714a7/src/transformers/models/t5/modeling_t5.py#LL316C15-L316C71
                    if module_name.endswith("wo"):
                        tensor = tensor.to(torch.float32)
                    else:
                        tensor = tensor.to(dtype)

                    if quantize == "bitsandbytes" and not module_name.endswith("wo"):
                        if not HAS_BITS_AND_BYTES:
                            raise ImportError(
                                "bitsandbytes is not available on your machine either because it is not installed "
                                "or you don't have a GPU.\n"
                                "You can install it with `pip install bitsandbytes`."
                            )

                        if (
                            type(module)
                            in [TensorParallelRowLinear, TensorParallelColumnLinear]
                            and param_name == "weight"
                        ):
                            tensor = Int8Params(
                                tensor,
                                has_fp16_weights=False,
                                requires_grad=False,
                            ).to(device)
                            state = bnb.MatmulLtState()
                            state.threshold = 6.0
                            state.has_fp16_weights = False
                            state.memory_efficient_backward = False
                            state.use_pool = True
                            state.CB = tensor.CB
                            state.SCB = tensor.SCB
                            tensor.CB = None
                            tensor.SCB = None

                            def replace_linear(state):
                                def linear(input, weight, bias):
                                    out = bnb.matmul(
                                        input,
                                        weight,
                                        state=state,
                                        threshold=state.threshold,
                                        bias=bias,
                                    )

                                    if state.CB is not None:
                                        # we converted 8-bit row major to turing/ampere format
                                        # in the first inference pass
                                        # we no longer need the row-major weight
                                        del state.CB
                                        weight.data = state.CxB

                                    return out

                                return linear

                            module.linear = replace_linear(state)

                        elif quantize == "gptq" and not module_name.endswith("wo"):
                            raise NotImplementedError(
                                "`gptq` is not implemented for now"
                            )
                        elif quantize is None:
                            tensor = tensor.to(device)
                        else:
                            raise ValueError(f"Unexpected quantize `{quantize}`")

                    if current_parameter_tensor is not None:
                        module._parameters[param_name] = tensor
                    else:
                        module._buffers[param_name] = tensor

    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,
        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,
        )

        # Logits are sharded, so we need to gather them
        logits = [torch.empty_like(outputs.logits) for _ in range(self.world_size)]
        torch.distributed.all_gather(logits, outputs.logits, group=self.process_group)
        logits = torch.cat(logits, dim=2)

        return (
            logits,
            outputs.encoder_last_hidden_state,
            outputs.past_key_values,
        )