transformers - ✅(Solved) Fix Why the calculation of train_batch_size unrelated to split_batches [1 pull requests, 2 comments, 2 participants]

Official PRs (…)
ON THIS PAGE

GitHub issue graph ai analysis

Paste a GitHub issue URL. We fetch that issue, discover linked issues from bodies/comments/timeline, collect linked pull requests, and produce a structured English report.

The report is written in English Markdown for sharing and archival.

Helpful · Quick feedback

Loading…
GitHub stats
huggingface/transformers#45693Fetched 2026-04-30 06:18:27
View on GitHub
Comments
2
Participants
2
Timeline
3
Reactions
0
Author
Timeline (top)
commented ×2cross-referenced ×1

Fix Action

Fixed

PR fix notes

PR #45694: Fix train_batch_size and eval_batch_size to respect split_batches config

Description (problem / solution / changelog)

Fixes #45693

Problem

When split_batches=True is set in accelerator_config, the train_batch_size and eval_batch_size properties were still multiplying per_device_batch_size by n_gpu, which is incorrect.

When split_batches=True, the batch is split across devices rather than replicated, so the total batch size equals per_device_batch_size directly.

Fix

Added a check for split_batches in both train_batch_size and eval_batch_size properties in TrainingArguments.

Testing

  • Added a new test test_batch_size_respects_split_batches
  • All 26 existing + new tests pass

Changed files

  • src/transformers/training_args.py (modified, +8/-2)
  • tests/trainer/test_training_args.py (modified, +21/-0)

Code Example

@property
    def train_batch_size(self) -> int:
        """
        The actual batch size for training.
        """
        train_batch_size = self.per_device_train_batch_size * max(1, self.n_gpu)
        return train_batch_size

---

if self.accelerator_config.split_batches:
                logger.info(
                    "Using `split_batches=True` in `accelerator_config` will override the `per_device_train_batch_size` "
                    "Batches will be split across all processes equally when using `split_batches=True`."
                )
RAW_BUFFERClick to expand / collapse

In the calculation of train_batch_size property in transformers/training_args.py, the formula used is train_batch_size = self.per_device_train_batch_size * max(1, self.n_gpu). When split_batches is set to False, this is easy to understand: the number of samples on each GPU multiplied by the number of GPUs equals the actual batch_size. However, when split_batches is set to True, the log message shows that Using split_batches=True in accelerator_config will override the per_device_train_batch_size , Batches will be split across all processes equally when using split_batches=True. My understanding is that when split_batches=True, the sample size on each GPU is per_device_train_batch_size // n_gpu, so the actual batch_size is just per_device_train_batch_size, without multiplying by n_gpu, why the calculation of train_batch_size property unrelated to split_batches, did I understand something wrongly? Thanks.

    @property
    def train_batch_size(self) -> int:
        """
        The actual batch size for training.
        """
        train_batch_size = self.per_device_train_batch_size * max(1, self.n_gpu)
        return train_batch_size
            if self.accelerator_config.split_batches:
                logger.info(
                    "Using `split_batches=True` in `accelerator_config` will override the `per_device_train_batch_size` "
                    "Batches will be split across all processes equally when using `split_batches=True`."
                )

extent analysis

TL;DR

The calculation of train_batch_size should consider the split_batches flag to accurately reflect the actual batch size during training.

Guidance

  • Review the calculation of train_batch_size to ensure it accounts for the split_batches flag, potentially adjusting the formula to train_batch_size = self.per_device_train_batch_size when split_batches is True.
  • Verify the logic by checking the batch size when split_batches is True and False to ensure it aligns with the expected behavior.
  • Consider adding a conditional statement to the train_batch_size property to handle the split_batches case, ensuring the batch size calculation is correct in both scenarios.
  • Evaluate the impact of split_batches on the training process and batch size to ensure it meets the requirements of the application.

Example

    @property
    def train_batch_size(self) -> int:
        """
        The actual batch size for training.
        """
        if self.accelerator_config.split_batches:
            train_batch_size = self.per_device_train_batch_size
        else:
            train_batch_size = self.per_device_train_batch_size * max(1, self.n_gpu)
        return train_batch_size

Notes

The provided code snippet and log message suggest that the split_batches flag affects the batch size calculation, but the current implementation does not account for this. The proposed solution aims to address this discrepancy.

Recommendation

Apply workaround: Modify the train_batch_size property to conditionally calculate the batch size based on the split_batches flag, as shown in the example code snippet. This ensures the actual batch size during training accurately reflects the configuration.

Vote matrix · Quick signals

Works
Did the solution work? Tap to confirm.
Easy Fix
Was it a quick fix?
Time Saver
Did it save you time?
Blocking
Was it severely blocking?
Common Issue
Are others likely hitting this too?
Flaky / Intermittent
Is it intermittent?
Verified / Reproducible
Can you reproduce it reliably?
Loading…

Still need to ship something?

×6

Another batch ranked right after the header list — different links, same matching logic.

Back to top recommendations

TRENDING