From 7180dc3f46e0ee33782fc3e8c97b224ff3ea5280 Mon Sep 17 00:00:00 2001
From: Orbax Authors <no-reply@google.com>
Date: Thu, 23 Apr 2026 02:13:21 -0700
Subject: [PATCH] No public description

PiperOrigin-RevId: 904321063
---
 .../_src/serialization/tensorstore_utils.py   | 12 ++++++
 .../serialization/tensorstore_utils_test.py   | 42 +++++++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/checkpoint/orbax/checkpoint/_src/serialization/tensorstore_utils.py b/checkpoint/orbax/checkpoint/_src/serialization/tensorstore_utils.py
index 1013584d3..bff9a165c 100644
--- a/checkpoint/orbax/checkpoint/_src/serialization/tensorstore_utils.py
+++ b/checkpoint/orbax/checkpoint/_src/serialization/tensorstore_utils.py
@@ -193,6 +193,18 @@ def build_kvstore_tspec(
         'driver': 'ocdbt',
         'base': base_driver_spec,
     })
+    # For OCDBT on local filesystems (including GCSFuse), we can safely use
+    # non-atomic writes for data files to avoid expensive renames. However,
+    # the manifest file still requires atomic writes to avoid corruption.
+    # We achieve this by splitting the spec into 'base' (for data files) and
+    # 'manifest'. Direct GCS paths ('gs://') do not need this optimization
+    # as they don't use the file driver.
+    if not is_gcs_path:
+      base_spec = copy.deepcopy(base_driver_spec)
+      if isinstance(base_spec, dict):
+        base_spec['file_io_locking'] = {'mode': 'non_atomic'}
+        kv_spec['base'] = base_spec
+        kv_spec['manifest'] = base_driver_spec
     if name is not None:
       kv_spec['path'] = name
 
diff --git a/checkpoint/orbax/checkpoint/_src/serialization/tensorstore_utils_test.py b/checkpoint/orbax/checkpoint/_src/serialization/tensorstore_utils_test.py
index 71c3a9424..98ce5251c 100644
--- a/checkpoint/orbax/checkpoint/_src/serialization/tensorstore_utils_test.py
+++ b/checkpoint/orbax/checkpoint/_src/serialization/tensorstore_utils_test.py
@@ -199,6 +199,48 @@ def test_ocdbt_kvstore(
     )
     self.assertEqual(json_tspec['kvstore']['path'], self.param_name)
 
+  def test_ocdbt_kvstore_with_non_atomic_locking(self):
+    tspec = self.array_write_spec_constructor(
+        directory=self.directory,
+        relative_array_filename=self.param_name,
+        use_zarr3=False,
+        use_ocdbt=True,
+        process_id=13,
+    )
+    self.assertTrue(tspec.metadata.use_ocdbt)
+    json_tspec = tspec.json
+    kvstore_tspec = json_tspec['kvstore']
+    self.assertEqual(kvstore_tspec['driver'], 'ocdbt')
+
+    # Base spec should have non_atomic locking
+    base_spec = kvstore_tspec['base']
+    self.assertEqual(base_spec['driver'], ts_utils.DEFAULT_DRIVER)
+    self.assertEqual(base_spec['file_io_locking'], {'mode': 'non_atomic'})
+
+    # Manifest spec should be present and NOT have non_atomic locking
+    self.assertIn('manifest', kvstore_tspec)
+    manifest_spec = kvstore_tspec['manifest']
+    self.assertEqual(manifest_spec['driver'], ts_utils.DEFAULT_DRIVER)
+    self.assertNotIn('file_io_locking', manifest_spec)
+
+  def test_ocdbt_kvstore_with_non_atomic_locking_gcs_path(self):
+    tspec = self.array_write_spec_constructor(
+        directory='gs://gcs_bucket/object_path',
+        relative_array_filename=self.param_name,
+        use_zarr3=False,
+        use_ocdbt=True,
+        process_id=0,
+    )
+    self.assertTrue(tspec.metadata.use_ocdbt)
+    kvstore_tspec = tspec.json['kvstore']
+    self.assertEqual(kvstore_tspec['driver'], 'ocdbt')
+
+    # Base should be a string (URL) and NOT have file_io_locking
+    self.assertIsInstance(kvstore_tspec['base'], str)
+
+    # Manifest should NOT be present in the spec
+    self.assertNotIn('manifest', kvstore_tspec)
+
   @parameterized.named_parameters(
       dict(
           testcase_name='regular_path',