set version for v0.9.1

* fix(log): clarify error on dataset loading failed

* fix: add path for easy tracking of broken config

* fix: improve error message based on pr feedback

.github/workflows/tests.yml

@@ -329,18 +329,6 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - cuda: 124
-            cuda_version: 12.4.1
-            python_version: "3.11"
-            pytorch: 2.6.0
-            num_gpus: 1
-            axolotl_extras: llmcompressor
-          - cuda: 124
-            cuda_version: 12.4.1
-            python_version: "3.11"
-            pytorch: 2.4.1
-            num_gpus: 1
-            axolotl_extras:
           - cuda: 124
             cuda_version: 12.4.1
             python_version: "3.11"

docs/custom_integrations.qmd

@@ -49,8 +49,7 @@ sections = [
     ("Knowledge Distillation (KD)", "kd"),
     ("Liger Kernels", "liger"),
     ("Language Model Evaluation Harness (LM Eval)", "lm_eval"),
-    ("Spectrum", "spectrum"),
-    ("LLMCompressor", "llm_compressor")
+    ("Spectrum", "spectrum")
 ]
 
 for section_name, folder_name in sections:

examples/llama-3/sparse-finetuning.yaml

@@ -1,77 +0,0 @@
-base_model: neuralmagic/Sparse-Llama-3.1-8B-2of4
-
-plugins:
-  - axolotl.integrations.llm_compressor.LLMCompressorPlugin
-
-load_in_8bit: false
-load_in_4bit: false
-strict: false
-
-datasets:
-  - path: tatsu-lab/alpaca
-    type: alpaca
-dataset_prepared_path: last_run_prepared
-val_set_size: 0.05
-output_dir: ./outputs/out
-
-sequence_len: 4096
-sample_packing: true
-pad_to_sequence_len: true
-eval_sample_packing: false
-
-wandb_project:
-wandb_entity:
-wandb_watch:
-wandb_name:
-wandb_log_model:
-
-gradient_accumulation_steps: 8
-micro_batch_size: 1
-num_epochs: 1
-optimizer: paged_adamw_8bit
-lr_scheduler: cosine
-learning_rate: 2e-5
-
-train_on_inputs: false
-group_by_length: false
-bf16: auto
-fp16:
-tf32: false
-
-gradient_checkpointing: true
-gradient_checkpointing_kwargs:
-  use_reentrant: false
-early_stopping_patience:
-resume_from_checkpoint:
-logging_steps: 1
-xformers_attention:
-flash_attention: true
-
-warmup_steps: 100
-evals_per_epoch: 2
-eval_table_size:
-saves_per_epoch: 1
-debug:
-deepspeed:
-weight_decay: 0.0
-fsdp:
-fsdp_config:
-special_tokens:
-  pad_token: <|end_of_text|>
-
-llmcompressor:
-  recipe:
-    finetuning_stage:
-      finetuning_modifiers:
-        ConstantPruningModifier:
-          targets: [
-            're:.*q_proj.weight',
-            're:.*k_proj.weight',
-            're:.*v_proj.weight',
-            're:.*o_proj.weight',
-            're:.*gate_proj.weight',
-            're:.*up_proj.weight',
-            're:.*down_proj.weight',
-          ]
-          start: 0
-  save_compressed: true

setup.py

@@ -150,9 +150,6 @@ extras_require = {
     "vllm": [
         "vllm==0.7.2",
     ],
-    "llmcompressor": [
-        "llmcompressor==0.5.1",
-    ],
 }
 
 install_requires, dependency_links, extras_require_build = parse_requirements(

src/axolotl/__init__.py

@@ -4,4 +4,4 @@ import pkgutil
 
 __path__ = pkgutil.extend_path(__path__, __name__)  # Make this a namespace package
 
-__version__ = "0.10.0.dev0"
+__version__ = "0.9.1"

src/axolotl/core/trainers/base.py

@@ -114,6 +114,8 @@ class AxolotlTrainer(
             packing_efficiency_estimate=self.args.sample_packing_efficiency,
             batch_max_len=batch_max_len,
             batch_size=batch_size,
+            group_size=self.args.sample_packing_group_size,
+            bin_size=self.args.sample_packing_bin_size,
             sequential=self.args.sample_packing_sequentially,
             drop_last=True,
         )

src/axolotl/integrations/llm_compressor/README.md

@@ -1,108 +0,0 @@
-# LLMCompressor Integration
-
-Fine-tune sparsified models in Axolotl using Neural Magic's [LLMCompressor](https://github.com/vllm-project/llm-compressor).
-
-This integration enables fine-tuning of models sparsified using LLMCompressor within the Axolotl training framework. By combining LLMCompressor's model compression capabilities with Axolotl's distributed training pipelines, users can efficiently fine-tune sparse models at scale.
-
-It uses Axolotl’s plugin system to hook into the fine-tuning flows while maintaining sparsity throughout training.
-
----
-
-## Requirements
-
-- Axolotl with `llmcompressor` extras:
-
-  ```bash
-  pip install "axolotl[llmcompressor]"
-  ```
-
-- Requires `llmcompressor >= 0.5.1`
-
-This will install all necessary dependencies to fine-tune sparsified models using the integration.
-
----
-
-## Usage
-
-To enable sparse fine-tuning with this integration, include the plugin in your Axolotl config:
-
-```yaml
-plugins:
-  - axolotl.integrations.llm_compressor.LLMCompressorPlugin
-
-llmcompressor:
-  recipe:
-    finetuning_stage:
-      finetuning_modifiers:
-        ConstantPruningModifier:
-          targets: [
-            're:.*q_proj.weight',
-            're:.*k_proj.weight',
-            're:.*v_proj.weight',
-            're:.*o_proj.weight',
-            're:.*gate_proj.weight',
-            're:.*up_proj.weight',
-            're:.*down_proj.weight',
-          ]
-          start: 0
-  save_compressed: true
-# ... (other training arguments)
-```
-
-This plugin **does not apply pruning or sparsification itself** — it is intended for **fine-tuning models that have already been sparsified**.
-
-Pre-sparsified checkpoints can be:
-- Generated using [LLMCompressor](https://github.com/vllm-project/llm-compressor)
-- Downloaded from [Neural Magic's Hugging Face page](https://huggingface.co/neuralmagic)
-- Any custom LLM with compatible sparsity patterns that you've created yourself
-
-To learn more about writing and customizing LLMCompressor recipes, refer to the official documentation:
-[https://github.com/vllm-project/llm-compressor/blob/main/README.md](https://github.com/vllm-project/llm-compressor/blob/main/README.md)
-
-### Storage Optimization with save_compressed
-
-Setting `save_compressed: true` in your configuration enables saving models in a compressed format, which:
-- Reduces disk space usage by approximately 40%
-- Maintains compatibility with vLLM for accelerated inference
-- Maintains compatibility with llmcompressor for further optimization (example: quantization)
-
-This option is highly recommended when working with sparse models to maximize the benefits of model compression.
-
-### Example Config
-
-See [`examples/llama-3/sparse-finetuning.yaml`](examples/llama-3/sparse-finetuning.yaml) for a complete example.
-
----
-
-## Inference with vLLM
-
-After fine-tuning your sparse model, you can leverage vLLM for efficient inference.
-You can also use LLMCompressor to apply additional quantization to your fine-tuned
-sparse model before inference for even greater performance benefits.:
-
-```python
-from vllm import LLM, SamplingParams
-
-prompts = [
-    "Hello, my name is",
-    "The president of the United States is",
-    "The capital of France is",
-    "The future of AI is",
-]
-sampling_params = SamplingParams(temperature=0.8, top_p=0.95)
-llm = LLM("path/to/your/sparse/model")
-outputs = llm.generate(prompts, sampling_params)
-
-for output in outputs:
-    prompt = output.prompt
-    generated_text = output.outputs[0].text
-    print(f"Prompt: {prompt!r}, Generated text: {generated_text!r}")
-```
-
-For more details on vLLM's capabilities and advanced configuration options, see the [official vLLM documentation](https://docs.vllm.ai/).
-
-## Learn More
-
-For details on available sparsity and quantization schemes, fine-tuning recipes, and usage examples, visit the official LLMCompressor repository:
-
-[https://github.com/vllm-project/llm-compressor](https://github.com/vllm-project/llm-compressor)

src/axolotl/integrations/llm_compressor/__init__.py

@@ -1,5 +0,0 @@
-"""Integration entry point for the LLMCompressor plugin."""
-
-from .plugin import LLMCompressorPlugin
-
-__all__ = ["LLMCompressorPlugin"]

src/axolotl/integrations/llm_compressor/args.py

@@ -1,40 +0,0 @@
-"""
-LLMCompressor and Sparse Finetuning config models.
-"""
-
-from typing import Any
-
-from pydantic import BaseModel, Field
-from typing_extensions import Annotated
-
-
-class CompressionArgs(BaseModel):
-    """Sparse Finetuning config for LLMCompressor."""
-
-    # Typing for recipe is set to Any due to:
-    # https://github.com/vllm-project/llm-compressor/issues/1319
-    recipe: Annotated[
-        Any,
-        Field(
-            description="The recipe containing the compression algorithms and hyperparameters to apply."
-        ),
-    ]
-
-    save_compressed: Annotated[
-        bool,
-        Field(
-            default=False,
-            description="Whether to save the compressed model after training.",
-        ),
-    ]
-
-
-class LLMCompressorArgs(BaseModel):
-    """LLMCompressor configuration BaseModel."""
-
-    llmcompressor: Annotated[
-        CompressionArgs,
-        Field(
-            description="Arguments enabling compression pathways through the LLM Compressor plugins"
-        ),
-    ]

src/axolotl/integrations/llm_compressor/plugin.py

@@ -1,171 +0,0 @@
-"""
-Sparse Finetuning plugin for Axolotl — enables handling of sparse neural networks
-by maintaining masks for zero weights during training.
-"""
-
-import logging
-from functools import wraps
-from typing import Any, Callable, Concatenate, ParamSpec, TypeVar
-
-from llmcompressor import active_session, create_session
-from llmcompressor.core import callbacks as session_callbacks
-from llmcompressor.recipe import Recipe
-from torch.nn import Module
-from transformers.trainer import Trainer
-from transformers.trainer_callback import TrainerCallback, TrainerControl, TrainerState
-from transformers.training_args import TrainingArguments
-
-from axolotl.integrations.base import BasePlugin
-
-P = ParamSpec("P")  # Params for generic function signatures
-R = TypeVar("R")  # Return type for generic function signatures
-
-LOG = logging.getLogger("axolotl.integrations.llm_compressor")
-
-
-class LLMCompressorCallbackHandler(TrainerCallback):
-    """
-    Trainer callback for Sparse Finetuning.
-    Maintains sparsity patterns during training by applying masks after optimization steps,
-    ensuring zero-weight updates are canceled out.
-    """
-
-    def __init__(self, trainer: Trainer, recipe: Any):
-        """
-        Initialize the Sparse Finetuning callback handler.
-
-        Args:
-            trainer (Trainer): Huggingface Trainer instance.
-            recipe (Recipe | dict): Sparse finetuning recipe to apply.
-        """
-        super().__init__()
-        self.trainer = trainer
-        self.recipe = (
-            Recipe.model_validate(recipe) if not isinstance(recipe, Recipe) else recipe
-        )
-        self.original_compute_loss = trainer.compute_loss
-        self.trainer.compute_loss = compute_loss_wrapper(self.trainer.compute_loss)
-        create_session()
-
-    def on_train_begin(
-        self,
-        args: TrainingArguments,
-        state: TrainerState,
-        control: TrainerControl,
-        **kwargs,
-    ) -> None:
-        """
-        Called at the beginning of training. Initializes the compression session.
-
-        Args:
-            args (TrainingArguments): Training arguments.
-            state (TrainerState): Trainer state.
-            control (TrainerControl): Trainer control.
-        """
-        super().on_train_begin(args, state, control, **kwargs)
-        self.trainer.accelerator.wait_for_everyone()
-        active_session().initialize(
-            model=self.trainer.model,
-            optimizer=self.trainer.optimizer,
-            start=state.epoch,
-            recipe=self.recipe,
-        )
-        self.trainer.accelerator.wait_for_everyone()
-
-    def on_step_begin(
-        self,
-        args: TrainingArguments,
-        state: TrainerState,
-        control: TrainerControl,
-        **kwargs,
-    ) -> None:
-        """
-        Called at the beginning of a training step. Triggers batch_start callback.
-        """
-        super().on_step_begin(args, state, control, **kwargs)
-        session_callbacks.batch_start()
-
-    def on_step_end(
-        self,
-        args: TrainingArguments,
-        state: TrainerState,
-        control: TrainerControl,
-        **kwargs,
-    ) -> None:
-        """
-        Called at the end of a training step. Triggers optimizer and batch_end callbacks.
-        """
-        super().on_step_end(args, state, control, **kwargs)
-        session_callbacks.optim_pre_step()
-        session_callbacks.optim_post_step()
-        session_callbacks.batch_end()
-
-    def on_train_end(
-        self,
-        args: TrainingArguments,
-        state: TrainerState,
-        control: TrainerControl,
-        **kwargs,
-    ) -> None:
-        """
-        Called at the end of training. Finalizes the compression session.
-        """
-        super().on_train_end(args, state, control, **kwargs)
-        active_session().finalize()
-        self.trainer.compute_loss_func = self.original_compute_loss
-
-
-class LLMCompressorPlugin(BasePlugin):
-    """
-    Sparse Finetuning plugin for Axolotl integration.
-    """
-
-    def get_input_args(self) -> str:
-        """
-        Returns the path to the plugin's argument definition.
-
-        Returns:
-            str: Dotted path to the LLMCompressorArgs class.
-        """
-        return "axolotl.integrations.llm_compressor.args.LLMCompressorArgs"
-
-    def add_callbacks_post_trainer(self, cfg: Any, trainer: Trainer) -> list:
-        """
-        Adds Sparse Finetuning callback to the Trainer instance.
-
-        Args:
-            cfg (Any): Configuration object containing the sparse recipe.
-            trainer (Trainer): Huggingface Trainer instance.
-
-        Returns:
-            list: List containing the configured callback instances.
-        """
-        LOG.info("Adding Sparse Finetuning callback to the trainer")
-        callback = LLMCompressorCallbackHandler(
-            trainer=trainer,
-            recipe=cfg.llmcompressor.recipe,
-        )
-        return [callback]
-
-
-def compute_loss_wrapper(
-    compute_loss_func: Callable[Concatenate[Module, P], R],
-) -> Callable[Concatenate[Module, P], R]:
-    """
-    Wraps the loss computation function to trigger the loss_calculated callback.
-
-    Args:
-        compute_loss_func (Callable): Original loss computation function.
-
-    Returns:
-        Callable: Wrapped function that also invokes the loss_calculated callback.
-    """
-
-    @wraps(compute_loss_func)
-    def compute_and_notify(model: Module, *args: P.args, **kwargs: P.kwargs) -> R:
-        loss = compute_loss_func(model, *args, **kwargs)
-        if active_session().lifecycle.initialized_ and model.training:
-            session_callbacks.loss_calculated(loss=loss)
-        return loss
-
-    return compute_and_notify

src/axolotl/integrations/llm_compressor/utils.py

@@ -1,40 +0,0 @@
-"""Utilities for llmcompressor integration with axolotl."""
-
-from typing import Union
-
-from llmcompressor.transformers.sparsification.compressed_tensors_utils import (
-    modify_save_pretrained,
-)
-from transformers import PreTrainedModel, Trainer
-
-
-def save_compressed_model(
-    model: PreTrainedModel,
-    output_dir: Union[str, bytes],
-    trainer: Trainer,
-    safe_serialization: bool = False,
-    save_compressed: bool = False,
-) -> None:
-    """
-    Synchronize processes, apply compression hooks, and save the model.
-
-    Args:
-        model (PreTrainedModel): The model to be saved.
-        output_dir (str or bytes): Path where the model files will be written.
-        trainer (Trainer): Hugging Face Trainer for process synchronization.
-        safe_serialization (bool): Use safe serialization if True.
-        save_compressed (bool): Write compressed tensors if True.
-    """
-    trainer.accelerator.wait_for_everyone()
-
-    # Only the main process writes the files
-    if not trainer.accelerator.is_main_process:
-        return
-
-    modify_save_pretrained(model)
-    model.save_pretrained(
-        output_dir,
-        safe_serialization=safe_serialization,
-        save_compressed=save_compressed,
-        skip_sparsity_compression_stats=not save_compressed,
-    )

src/axolotl/train.py

@@ -294,23 +294,8 @@ def save_trained_model(
             trainer.model.save_pretrained(
                 cfg.output_dir, safe_serialization=safe_serialization
             )
-
         model.save_pretrained(cfg.output_dir, safe_serialization=safe_serialization)
 
-    if hasattr(cfg, "llmcompressor") and cfg.llmcompressor:
-        # TODO: add integration support so this can be implemented completely within the plugin
-        from axolotl.integrations.llm_compressor.utils import (
-            save_compressed_model,
-        )
-
-        save_compressed_model(
-            model=model,
-            output_dir=cfg.output_dir,
-            trainer=trainer,
-            safe_serialization=safe_serialization,
-            save_compressed=cfg.llmcompressor.save_compressed,
-        )
-
 
 def create_model_card(cfg: DictDefault, trainer: Trainer):
     """

src/axolotl/utils/models.py

@@ -141,22 +141,6 @@ def check_model_config(cfg: DictDefault, model_config: PretrainedConfig):
         hasattr(model_config, "quantization_config")
         and model_config.quantization_config
     )
-
-    # Detect compressed-tensors config
-    is_compressed_tensors_config = (
-        quant_config_exists
-        and model_config.quantization_config.get("quant_method") == "compressed-tensors"
-    )
-
-    if is_compressed_tensors_config:
-        if model_config.quantization_config.get("config_groups"):
-            LOG.warning(
-                "Found `config_groups` in a compressed-tensors config. "
-                "QAT integration with llmcompressor is not tested."
-            )
-        # Skip further quant checks for compressed-tensors
-        return
-
     quant_config_method_is_gptq = (
         quant_config_exists
         and "quant_method" in model_config.quantization_config

src/axolotl/utils/samplers/multipack.py

@@ -1,10 +1,13 @@
-# pylint: skip-file
 """
-Multipack Batch Sampler
+Multipack Batch Sampler - An efficient batch sampler for packing variable-length sequences
+into fixed-capacity batches to optimize memory usage and training throughput.
 """
+
 import logging
 import math
-from typing import Any, Iterable, List, Union
+from concurrent.futures import ProcessPoolExecutor
+from multiprocessing import cpu_count
+from typing import Iterable, Union
 
 import numba
 import numpy as np
@@ -13,26 +16,39 @@ from torch.utils.data import BatchSampler, Sampler, SequentialSampler
 from axolotl.utils.distributed import reduce_and_broadcast
 
 LOG = logging.getLogger(__name__)
-
 LOG.setLevel(logging.INFO)
 
 
 @numba.njit
-def ffd_check(a: np.ndarray, c: int, n: int):
-    # First-fit-decreasing bin packing
-    # Check if a[] could fit in n bins with capacity c
-    # https://en.wikipedia.org/wiki/First-fit-decreasing_bin_packing
+def ffd_check(sequence_lengths: np.ndarray, bin_capacity: int, num_bins: int):
+    """
+    First-fit-decreasing bin packing algorithm check
 
-    a = np.sort(a)[::-1]
-    bins = np.full((n,), c, dtype=a.dtype)
-    for size in a:
+    Checks if sequences with the given lengths could fit in the specified number of bins
+
+    Args:
+        sequence_lengths: Array of sequence lengths
+        bin_capacity: Maximum capacity of each bin
+        num_bins: Number of bins available
+
+    Returns:
+        True if all sequences can be packed, False otherwise
+    """
+    # Sort sequence lengths in descending order for optimal packing
+    sequence_lengths = np.sort(sequence_lengths)[::-1]
+    # Initialize all bins with full capacity
+    bins = np.full((num_bins,), bin_capacity, dtype=sequence_lengths.dtype)
+
+    # Try to place each sequence in the first bin it fits
+    for size in sequence_lengths:
         not_found = True
-        for idx in range(n):
+        for idx in range(num_bins):
             if bins[idx] >= size:
                 bins[idx] -= size
                 not_found = False
                 break
 
+        # If no bin could fit this sequence, packing failed
         if not_found:
             return False
 
@@ -40,86 +56,132 @@ def ffd_check(a: np.ndarray, c: int, n: int):
 
 
 @numba.njit
-def ffd_with_result(a: np.ndarray, c: int, start_index: int):
-    # First-fit-decreasing bin packing (with result return)
+def pack_group(
+    sequence_lengths: np.ndarray,
+    group_offset: int,
+    bin_capacity: int,
+    max_bins: int,
+    bin_size: int,
+    safe_mode: bool = True,
+):
+    """
+    Pack a group of sequences into bins using First-Fit Decreasing algorithm
 
-    indices = np.argsort(a)[::-1]
-    a = a[indices]
+    Args:
+        sequence_lengths: Array of sequence lengths
+        group_offset: Offset to apply to indices when returning results
+        bin_capacity: Maximum capacity of each bin
+        max_bins: Maximum number of bins to use
+        bin_size: Maximum number of sequences per bin
+        safe_mode: If True, use a more conservative packing approach
 
-    bins: List[Any] = []
-    bins_result: List[Any] = []
-    for a_id, size in enumerate(a):
-        add_new = True
-        for idx in range(len(bins)):
-            if bins[idx] >= size:
-                bins[idx] -= size
-                bins_result[idx].append(indices[a_id] + start_index)
-                add_new = False
+    Returns:
+        List of bins, where each bin contains indices of sequences assigned to it
+    """
+    # Get sorting indices and sort lengths in descending order
+    indices = np.argsort(sequence_lengths)[::-1]
+    sorted_lengths = sequence_lengths[indices]
+
+    bins_remaining_space: list = []  # Tracks remaining capacity in each bin
+    bins_assigned_sequences: list = []  # Tracks sequence indices assigned to each bin
+
+    for seq_id, size in enumerate(sorted_lengths):
+        global_idx = indices[seq_id] + group_offset
+
+        # Try to place sequence in existing bins
+        add_new_bin = True
+        for bin_idx, _ in enumerate(bins_remaining_space):
+            if (
+                bins_remaining_space[bin_idx] >= size
+                and len(bins_assigned_sequences[bin_idx]) < bin_size
+            ):
+                bins_remaining_space[bin_idx] -= size
+                bins_assigned_sequences[bin_idx].append(global_idx)
+                add_new_bin = False
                 break
 
-        if add_new:
-            bins.append(c - size)
-            bins_result.append([indices[a_id] + start_index])
+        # Create a new bin if needed and if we haven't reached the limit
+        if add_new_bin:
+            if len(bins_remaining_space) >= max_bins and safe_mode:
+                # In safe mode, skip items that would exceed max_bins
+                continue
+            bins_remaining_space.append(bin_capacity - size)
+            bins_assigned_sequences.append([global_idx])
 
-    return bins_result
+            # Safety check to avoid infinite bins
+            if len(bins_remaining_space) > len(sequence_lengths):
+                break
+
+    return bins_assigned_sequences
 
 
-@numba.njit
-def allocate(
-    lengths: np.ndarray, lengths_cumsum: np.ndarray, rank: int, c: int, n: int
+# Define a standalone function for multiprocessing
+def _process_group(args):
+    group_lengths, start_idx, bin_capacity, max_bins, bin_size, safe_mode = args
+    return pack_group(
+        group_lengths, start_idx, bin_capacity, max_bins, bin_size, safe_mode
+    )
+
+
+def pack_parallel(
+    sequence_lengths: np.ndarray,
+    bin_capacity: int,
+    group_size: int,
+    bin_size: int,
+    num_processes: int | None = None,
+    safe_mode: bool = True,
 ):
-    # Dynamic batch allocator, similar to Multifit
-    # https://en.wikipedia.org/wiki/Multifit_algorithm
-    # ~99.5% efficiency on OpenChat training set (12 * 2048 ctx len)
+    """
+    Pack sequences into bins using parallel processing
 
-    s = 0
-    start_index = 0
-    result = []
+    Args:
+        sequence_lengths: Array of sequence lengths
+        bin_capacity: Maximum capacity of each bin as total number of tokens
+        group_size: Number of sequences to process in each group
+        bin_size: Maximum number of bins to use
+        num_processes: Number of parallel processes to use
+        safe_mode: If True, use a more conservative packing approach
 
-    while True:
-        # binary search [l, r)
-        left = 1
-        right = 1 + np.searchsorted(lengths_cumsum[start_index:], s + c * n, "right")
+    Returns:
+        List of bins, where each bin contains indices of sequences assigned to it
+    """
+    num_items = len(sequence_lengths)
+    if num_processes is None:
+        num_processes = max(1, min(num_items // group_size, cpu_count()))
 
-        while right - left > 1:
-            mid = (left + right) // 2
-            if ffd_check(lengths[start_index : start_index + mid], c, n):
-                left = mid
-            else:
-                right = mid
+    # Create tasks for parallel processing
+    tasks = []
+    for i in range(0, num_items, group_size):
+        group_lengths = sequence_lengths[i : i + group_size]
+        max_bins = len(group_lengths)  # Allow as many bins as items in the group
+        tasks.append((group_lengths, i, bin_capacity, max_bins, bin_size, safe_mode))
 
-        # use length l
-        batch = ffd_with_result(
-            lengths[start_index : start_index + left], c, start_index
-        )
-        assert len(batch) <= n
-        if len(batch) < n:
-            break
+    # Process groups in parallel
+    all_bins = []
+    with ProcessPoolExecutor(max_workers=num_processes) as executor:
+        for group_bins in executor.map(_process_group, tasks):
+            all_bins.extend(group_bins)
 
-        start_index += left
-        s = lengths_cumsum[start_index - 1]
-
-        # add local rank
-        result.append(batch[rank])
-
-    return result, s, len(result) * c * n
+    return all_bins
 
 
 @numba.njit
-def allocate_sequentially(lengths: np.ndarray, rank: int, c: int, n: int):
+def allocate_sequentially(
+    sequence_lengths: np.ndarray, rank: int, bin_capacity: int, num_ranks: int
+):
     """
     Sequential allocator that preserves example order
 
-    Parameters:
-    - lengths: The lengths of all examples
-    - rank: The current rank (for distributed training)
-    - c: The capacity of each bin (maximum sequence length)
-    - n: Number of ranks
+    Args:
+        sequence_lengths: The lengths of all examples
+        rank: The current rank (for distributed training)
+        bin_capacity: The capacity of each bin (maximum sequence length)
+        num_ranks: Number of ranks (processes/GPUs)
 
     Returns:
-    - result: List of batches for the current rank
-    - total_used: Number of actual example tokens
-    - total_slots: Maximum theoretical number of example tokens (number of bins * bin capacity)
+        rank_batches: List of batches for the current rank
+        total_tokens_used: Number of actual example tokens
+        total_token_slots: Maximum theoretical number of example tokens (number of bins * bin capacity)
     """
     result = []
     total_used = 0
@@ -127,9 +189,9 @@ def allocate_sequentially(lengths: np.ndarray, rank: int, c: int, n: int):
     # First, do sequential packing into bins
     all_bins = []
     current_bin = [0 for i in range(0)]  # numba hint
-    remaining_capacity = c
+    remaining_capacity = bin_capacity
 
-    for idx, size in enumerate(lengths):
+    for idx, size in enumerate(sequence_lengths):
         if size <= remaining_capacity:
             # Example fits in current bin
             current_bin.append(idx)
@@ -140,7 +202,7 @@ def allocate_sequentially(lengths: np.ndarray, rank: int, c: int, n: int):
             if current_bin:  # Add non-empty bin to all_bins
                 all_bins.append(current_bin)
             current_bin = [idx]
-            remaining_capacity = c - size
+            remaining_capacity = bin_capacity - size
             total_used += size
 
     # Add the last bin if not empty
@@ -148,132 +210,227 @@ def allocate_sequentially(lengths: np.ndarray, rank: int, c: int, n: int):
         all_bins.append(current_bin)
 
     # Assign bins to ranks - each rank gets every n-th bin
-    for bin_idx in range(rank, len(all_bins), n):
+    for bin_idx in range(rank, len(all_bins), num_ranks):
         result.append(all_bins[bin_idx])
 
-    return result, total_used, len(all_bins) * c
+    return result, total_used, len(all_bins) * bin_capacity
 
 
 class MultipackBatchSampler(BatchSampler):
-    """Batch sampler class for multipack"""
+    """
+    Batch sampler class for efficient packing of variable-length sequences
+
+    This sampler packs sequences into fixed-capacity bins (batches) to maximize
+    GPU memory utilization and training throughput by reducing padding.
+
+    It supports both parallel packing (using FFD algorithm) and
+    sequential packing (preserving original sequence order).
+    """
 
     def __init__(
         self,
         sampler: Union[Sampler[int], Iterable[int]],
-        batch_size: int,
-        batch_max_len: int,
-        lengths: np.ndarray,
-        packing_efficiency_estimate: float = 1.0,
-        drop_last: bool = False,
-        num_count_samples: int = 16,
-        sequential: bool = False,
-        **kwargs,
+        batch_size: int,  # Number of bins per batch
+        batch_max_len: int,  # Maximum sequence length (bin capacity)
+        lengths: np.ndarray,  # Sequence lengths
+        packing_efficiency_estimate: float = 1.0,  # Initial efficiency estimate
+        drop_last: bool = False,  # Whether to drop final batches (might be incomplete)
+        num_count_samples: int = 16,  # Number of times to estimate batch count
+        sequential: bool = False,  # Whether to use sequential packing
+        group_size: int = 100_000,  # Size of groups for parallel packing
+        bin_size: int = 200,  # The max number of samples that can be packed in a single bin
+        num_processes: int | None = None,  # Number of processes for parallel packing
+        safe_mode: bool = True,  # Conservative packing to prevent training instability
+        **kwargs,  # pylint: disable=unused-argument
     ):
         super().__init__(sampler, batch_size, drop_last)
         self.batch_size = batch_size
         self.batch_max_len = batch_max_len
-        self.lengths: np.ndarray = lengths
+        self.lengths = np.array(lengths, dtype=np.int32)
         self.packing_efficiency_estimate = packing_efficiency_estimate or 1.0
         self.sequential = sequential
+        self.group_size = group_size
+        self.bin_size = bin_size
+        self.num_processes = num_processes
+        self.safe_mode = safe_mode
 
         assert isinstance(self.lengths, np.ndarray)
 
         self.epoch = 0
 
-        # statistics
-        self.eff_total_used = 0
-        self.eff_total_slots = 0
+        # Efficiency statistics tracking
+        self.total_tokens_used = 0
+        self.total_token_slots = 0
 
-        # The number of times to calculate the batches to determine the minimum packed dataset length for the local rank
+        # The number of times to calculate batches to determine minimum packed dataset length
         self.num_count_samples = num_count_samples
-        # the minimum packed dataset length across all ranks determined by a gather/broadcast
+        # Minimum packed dataset length across all ranks (determined by gather/broadcast)
         self.len_across_ranks = None
 
+        # Cache for batches
+        self._batches = None
+
         if self.sequential and not isinstance(sampler, SequentialSampler):
             LOG.warning(
                 "using sequential sample packing with non-sequential sampler, did you want to also enable curriculum_sampling?"
             )
 
     def set_epoch(self, epoch: int):
+        """Set the epoch number, used for reproducible shuffling across epochs"""
         self.epoch = epoch
+        self._batches = None  # Invalidate batch cache
 
     def generate_batches(self, set_stats=False):
-        indices = [idx for idx in self.sampler]
+        """
+        Generate packed batches for training
 
-        lengths = self.lengths[indices]
-        lengths_cumsum = np.cumsum(lengths)
+        Args:
+            set_stats: Whether to update efficiency statistics
 
-        if self.sequential:
-            batches, total_used, total_slots = allocate_sequentially(
-                lengths=lengths,
-                rank=0,
-                c=self.batch_max_len,
-                n=1,
-            )
-        else:
-            batches, total_used, total_slots = allocate(
-                lengths=lengths,
-                lengths_cumsum=lengths_cumsum,
-                rank=0,
-                c=self.batch_max_len,
-                n=1,
-            )
+        Returns:
+            List of batches, where each batch contains multiple bins,
+            and each bin contains multiple sequence indices
+        """
+        if self._batches is not None:
+            return self._batches
 
-        batches = [
-            [
-                [indices[b_idx] for b_idx in batch]
-                for batch in batches[i : i + self.batch_size]
-            ]
-            for i in range(0, len(batches), self.batch_size)
+        # Get indices from the sampler
+        indices = [  # pylint: disable=unnecessary-comprehension
+            idx for idx in self.sampler
         ]
 
-        # statistics
-        if set_stats:
-            self.eff_total_used += total_used
-            self.eff_total_slots += total_slots
+        # Get lengths of the selected sequences
+        lengths = self.lengths[indices]
 
+        # Pack sequences into bins using either sequential or parallel packing
+        if self.sequential:
+            bins, total_used, total_slots = allocate_sequentially(
+                lengths,
+                rank=0,
+                bin_capacity=self.batch_max_len,
+                num_ranks=1,
+            )
+            # Map bin indices back to original indices
+            bins = [[indices[b_idx] for b_idx in bin_indices] for bin_indices in bins]
+        else:
+            # Use parallel packing
+            all_bins = pack_parallel(
+                lengths,
+                bin_capacity=self.batch_max_len,
+                group_size=self.group_size,
+                bin_size=self.bin_size,
+                num_processes=self.num_processes,
+                safe_mode=self.safe_mode,
+            )
+
+            # Map bin indices back to original indices
+            bins = [
+                [indices[b_idx] for b_idx in bin_indices] for bin_indices in all_bins
+            ]
+
+            # Calculate efficiency statistics
+            total_used = lengths.sum()
+            total_slots = len(all_bins) * self.batch_max_len
+
+        # Group bins into batches (each batch contains batch_size bins)
+        batches = [
+            bins[i : i + self.batch_size] for i in range(0, len(bins), self.batch_size)
+        ]
+
+        # Drop last batch if requested and it's incomplete
+        if self.drop_last and len(batches[-1]) < self.batch_size:
+            batches = batches[:-1]
+            # Adjust total_slots if we dropped a batch
+            if not self.sequential:
+                total_slots -= (self.batch_size - len(batches[-1])) * self.batch_max_len
+
+        # Update statistics if requested
+        if set_stats:
+            self.total_tokens_used += total_used
+            self.total_token_slots += total_slots
+
+        self._batches = batches
         return batches
 
     def __iter__(self):
+        """
+        Return an iterator over batches
+
+        The batches are truncated to match the minimum number of batches across all ranks
+        to ensure distributed training balance
+        """
         batches = self.generate_batches(set_stats=True)
         if self.len_across_ranks:
-            # make sure the batches we iterate over is truncated to the same min length across all ranks
+            # Truncate batches to ensure all ranks have the same number of batches
             batches = batches[: self.len_across_ranks]
         return iter(batches)
 
-    def num_batches(self):
-        batches = self.generate_batches(set_stats=True)
-        return len(batches)
-
     def efficiency(self):
-        return self.eff_total_used / self.eff_total_slots
+        """
+        Calculate the packing efficiency (ratio of tokens used to total token slots)
+        Higher is better - 1.0 would mean perfect packing with no wasted space
+        """
+        if self.total_token_slots == 0:
+            self.generate_batches(set_stats=True)
+        if self.total_token_slots == 0:
+            return 0.0
+        # Return a Python float instead of potentially a numpy float
+        return float(self.total_tokens_used / self.total_token_slots)
 
     def gather_efficiency(self):
-        def calc_sample_packing_eff_est(estimates: List[float]):
-            LOG.debug(f"sample_packing_eff_est across ranks: {repr(estimates)}")
-            return math.floor(0.997 * max(estimates))
+        """
+        Gather and synchronize packing efficiency estimates across all distributed ranks
+        Returns a conservative efficiency estimate based on the measurements
+        """
 
+        def calc_sample_packing_eff_est(estimates: list[float]):
+            LOG.debug(f"sample_packing_eff_est across ranks: {repr(estimates)}")
+            # Use 99.7% of max observed efficiency as a safe estimate
+            max_eff = max(float(eff) for eff in estimates)
+            return math.floor(0.997 * max_eff)
+
+        # Gather efficiency from all ranks and apply the calculation function
         sample_packing_actual_eff_all = reduce_and_broadcast(
-            lambda: self.efficiency(),  # pylint: disable=unnecessary-lambda
+            lambda: float(self.efficiency()),  # pylint: disable=unnecessary-lambda
             calc_sample_packing_eff_est,
         )
+
+        # Quantize to 0.5% intervals for stability
         sample_packing_eff_est = (
             math.ceil(sample_packing_actual_eff_all * 200.0) / 200.0
         )
         return sample_packing_eff_est
 
     def gather_len_batches(self, num):
+        """
+        Gather and synchronize batch counts across all distributed ranks
+        Returns the minimum number of batches available on any rank
+        """
+
         def calc_min_len(estimates: list[(int, float)]):
             LOG.info(f"gather_len_batches: {repr(estimates)}")
             return math.floor(min(estimates))
 
+        # Find minimum batch count across ranks to ensure balance
         min_len_batches = reduce_and_broadcast(lambda: num, calc_min_len)
         return min_len_batches
 
     def __len__(self):
-        if not self.len_across_ranks:
-            len_batches = min(
-                [self.num_batches() for _ in range(self.num_count_samples)]
+        """
+        Return the total number of batches that will be yielded by this sampler
+
+        This is calculated as the minimum number of batches available on any rank
+        to ensure balanced distributed training
+        """
+        if self._batches is None:
+            self._batches = self.generate_batches(set_stats=True)
+
+        if self.len_across_ranks is None:
+            # Sample multiple times to get stable estimate
+            len_batches = min(  # pylint: disable=consider-using-generator
+                [len(self._batches) for _ in range(self.num_count_samples)]
             )
+            # Gather minimum across all ranks
             self.len_across_ranks = self.gather_len_batches(len_batches)
+
         return self.len_across_ranks

tests/e2e/integrations/test_llm_compressor.py

@@ -1,111 +0,0 @@
-"""
-E2E smoke tests for LLMCompressorPlugin integration
-"""
-
-from pathlib import Path
-
-import pytest
-
-from axolotl.cli.args import TrainerCliArgs
-from axolotl.common.datasets import load_datasets
-from axolotl.train import train
-from axolotl.utils.config import normalize_config, prepare_plugins, validate_config
-from axolotl.utils.dict import DictDefault
-
-from tests.e2e.utils import (
-    check_model_output_exists,
-    require_llmcompressor,
-    require_torch_2_4_1,
-)
-
-MODELS = [
-    "nm-testing/llama2.c-stories42M-pruned2.4-compressed",
-    "nm-testing/llama2.c-stories42M-gsm8k-sparse-only-compressed",
-]
-
-
-@pytest.mark.parametrize(
-    "base_model", MODELS, ids=["no-checkpoint-recipe", "with-checkpoint-recipe"]
-)
-@pytest.mark.parametrize(
-    "save_compressed", [True, False], ids=["save_compressed", "save_uncompressed"]
-)
-class TestLLMCompressorIntegration:
-    """
-    e2e tests for axolotl.integrations.llm_compressor.LLMCompressorPlugin
-    """
-
-    @require_llmcompressor
-    @require_torch_2_4_1
-    def test_llmcompressor_plugin(
-        self, temp_dir, base_model: str, save_compressed: bool
-    ):
-        from llmcompressor import active_session
-
-        # core cfg
-        cfg = DictDefault(
-            {
-                "base_model": base_model,
-                "plugins": ["axolotl.integrations.llm_compressor.LLMCompressorPlugin"],
-                "sequence_len": 1024,
-                "val_set_size": 0.05,
-                "special_tokens": {"pad_token": "<|endoftext|>"},
-                "datasets": [{"path": "mhenrichsen/alpaca_2k_test", "type": "alpaca"}],
-                "num_epochs": 1,
-                "micro_batch_size": 2,
-                "gradient_accumulation_steps": 2,
-                "output_dir": temp_dir,
-                "learning_rate": 1e-5,
-                "optimizer": "adamw_torch_fused",
-                "lr_scheduler": "cosine",
-                "save_safetensors": True,
-                "bf16": "auto",
-                "max_steps": 5,
-                "llmcompressor": {
-                    "recipe": {
-                        "finetuning_stage": {
-                            "finetuning_modifiers": {
-                                "ConstantPruningModifier": {
-                                    "targets": [
-                                        "re:.*q_proj.weight",
-                                        "re:.*k_proj.weight",
-                                        "re:.*v_proj.weight",
-                                        "re:.*o_proj.weight",
-                                        "re:.*gate_proj.weight",
-                                        "re:.*up_proj.weight",
-                                        "re:.*down_proj.weight",
-                                    ],
-                                    "start": 0,
-                                },
-                            },
-                        },
-                    },
-                    "save_compressed": save_compressed,
-                },
-            }
-        )
-
-        prepare_plugins(cfg)
-        cfg = validate_config(cfg)
-        normalize_config(cfg)
-        cli_args = TrainerCliArgs()
-        dataset_meta = load_datasets(cfg=cfg, cli_args=cli_args)
-
-        try:
-            train(cfg=cfg, dataset_meta=dataset_meta)
-            check_model_output_exists(temp_dir, cfg)
-            _check_llmcompressor_model_outputs(temp_dir, save_compressed)
-        finally:
-            active_session().reset()
-
-
-def _check_llmcompressor_model_outputs(temp_dir, save_compressed):
-    if save_compressed:
-        assert (Path(temp_dir) / "recipe.yaml").exists()
-
-        from compressed_tensors import ModelCompressor
-        from compressed_tensors.config import Sparse24BitMaskConfig
-
-        compressor = ModelCompressor.from_pretrained(temp_dir)
-        assert compressor is not None
-        assert isinstance(compressor.sparsity_config, Sparse24BitMaskConfig)

tests/e2e/utils.py

@@ -105,25 +105,7 @@ def require_vllm(test_case):
             return False
 
     return unittest.skipUnless(
-        is_vllm_installed(), "test requires vllm to be installed"
-    )(test_case)
-
-
-def require_llmcompressor(test_case):
-    """
-    Decorator marking a test that requires a llmcompressor to be installed
-    """
-
-    def is_llmcompressor_installed():
-        try:
-            import llmcompressor  # pylint: disable=unused-import  # noqa: F401
-
-            return True
-        except ImportError:
-            return False
-
-    return unittest.skipUnless(
-        is_llmcompressor_installed(), "test requires llmcompressor to be installed"
+        is_vllm_installed(), "test requires a vllm to be installed"
     )(test_case)