orbax-checkpoint

[0.12.3] - 2026-08-11

Added

• Add AtomicityOptions and AtomicityMode (AUTO, COMMIT_FILE,
  ATOMIC_RENAME) to configure the checkpoint save atomicity protocol in
  both v0 and v1.
• Write commit_success.txt on all newly finalized checkpoints across all
  storage backends, enabling cross-backend reading compatibility.
• Add allow_legacy_atomic_rename option to AtomicityOptions to opt into
  legacy fallback validation when reading legacy AtomicRename checkpoints
  missing commit_success.txt.
• Add multi_tier_checkpointing_backup_interval_steps parameter

Changed

• Deprecate temporary_path_class in CheckpointManagerOptions in favor of
  atomicity_options with AtomicityMode.

[0.12.2] - 2026-07-30

Added

• Reduce Memory Pressure from long held CPU buffers in Pathways MTC
• Support explicit devices for Pathways MTC init
• Avoid stale Pathways MTC worker dummy handles

Changed

• #v1 Drive the safetensors load by the target sharding: each process reads
  only the byte ranges its own devices need (coalesced under
  SafetensorsOptions.max_over_read_ratio, picked per file from the planned
  reads by default, fetched as concurrent ranged reads of
  SafetensorsOptions.read_chunk_bytes each, bounded by
  MemoryOptions.read_concurrent_bytes), replacing the transient-array
  resharding load. Supports arbitrary shardings, including inner-dimension
  partitions; a warning reports shardings whose fragmented byte layout forces
  heavy over-read.

Added

• Support for gcs_grpc driver.
• #v1 Add stringent validation for state abstract and concrete leaf types.
• Update MTC w/ Pathways to Support Scale Elasticity.

Added

• Add LatestDuration preservation policy to support duration-based (TTL)
  checkpoint retention.
• Add EveryNStepsClosest preservation policy, which preserves checkpoints at
  steps closest to multiples of interval_steps.
• Add SerializationStatusCallback for save operations to track transfer and
  disk write events. While primarily intended as lightweight progress handles,
  this callback system allows the potential to inject custom logic for
  advanced monitoring and custom actions during checkpointing.

Changed

• #v1 Rename save/load_pytree to save/load. Eliminate most user-facing
  "pytree" terminology in favor of "state" as a more specific term.
  Add deprecations.py for handling deprecated public functions.

Fixed

• Fix Pathways MTC Colocated worker initialization and save/restore PyTree bugs.
• Fix bug where TensorStore transaction was never used, due to byte_limiter
  always having a non-None value.

Removed

• #v1 Remove numpy and pytorch layouts, as these are insecure and not worth the
  effort in maintaining. Safetensors is instead the recommended conversion case.
• #v1 Remove LeafHandler as a user-exposed layer (it remains as an internal layer).

Added

• #v1 Allow a context to be default-configured for all Checkpointer
  operations.

Changed

• Upgrade to TensorStore>=0.1.84 (and Python>=3.11 as a consequence.)

Added

• Tensorstore non-atomic file I/O locking on local/POSIX-compatible filesystems
  to avoid unnecessary renames.

Added

• Add colocated runtime helpers for Pathways MTC.
• #v1 Centralize StorageOptions into ArrayOptions and implement field-level merging.
• Add Patch for Pathways CPU ids.
• Add sidecar MTC backend support
• Add Colocated Python Sidecar MTC Checkpoint Manager
• Add Colocated Python Orchestration handling
• #v1 Add LeafHandler as a CheckpointableHandler, so that ordinary PyTree leaves can also be saved as individual checkpointables.
• Move MTC files to multi_tier_checkpointing and use local checkpoint engine

Changed

• Reduced default OCDBT target file size from 2GiB to 400MiB for GCS paths.

Added

• #v1 Add auto loading functionality to load_pytree and pytree_metadata.

Added

• Add PyTorch DCP (Distributed Checkpoint) to the benchmark suite, with GCS
  connector and fsspec options.
• Eliminate unadvertised flax dependency from tree/utils.

Fixed

• #v1 Fix import path for step in orbax.checkpoint.experimental.v1.path.

Increment Orbax version.

PiperOrigin-RevId: 896170688

Increment Orbax version.

PiperOrigin-RevId: 871625440