# vacancy/Synchronized-BatchNorm-PyTorch

Synchronized Batch Normalization implementation in PyTorch.

Repository: https://github.com/vacancy/Synchronized-BatchNorm-PyTorch
Canonical: https://ross.abutalabs.com/products/synchronized-batchnorm-pytorch
Language: Python
License: MIT
License Family: permissive
Last push: 2021-04-08T19:24:36+00:00

## Health v2 (maintenance only)
Score: 32/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 35, longevity 100
- inputs: {"age_days": 3141, "days_push": 1973, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1502, forks 188 (observed 2026-08-28T04:04:54.506368+00:00)

## What it is
A PyTorch library implementing Synchronized Batch Normalization, which computes batch statistics across all GPUs during multi-device training instead of per-device. It provides drop-in replacement modules and a DataParallel wrapper with replication callbacks.

## Use cases
- train object detection models with small per-GPU batch sizes
- normalize batch statistics across multiple GPUs in PyTorch
- improve segmentation model training with tiny batches per device
- convert existing PyTorch models to use synchronized batchnorm
- reproduce MegDet-style large mini-batch training

## When to choose
- training on multiple GPUs with small per-device batch sizes where batch statistics matter
- using nn.DataParallel and needing cross-device normalization
- research prototypes needing sync batchnorm before native PyTorch support

## When to avoid
- single-GPU or CPU training (built-in BatchNorm is identical)
- new projects that can use PyTorch's native SyncBatchNorm
- production systems needing actively maintained dependencies
- DistributedDataParallel workflows with native support

## Facets
- artifact type: library
- maturity: maintenance
- function: machine-learning, deep-learning
- domain: deep-learning, computer-vision, machine-learning
- platform: python, cross-platform
- tags: pytorch, batch-normalization, multi-gpu, data-parallel, sync-bn, gpu

## Member repositories
- vacancy/Synchronized-BatchNorm-PyTorch (main) score 32

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:54.506368+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T04:32:55.188139+00:00, confidence not recorded.
  - readme: https://github.com/vacancy/Synchronized-BatchNorm-PyTorch (fetched 2026-08-28T04:04:54.506368+00:00, sha 00e57af84bc4)
- Data as of 2026-08-30T08:39:29.467469+00:00.