Add a check to prevent zero-sized arrays from being saved. This behav…

…ior already resulted in an error, but it was one that was difficult to parse.

PiperOrigin-RevId: 721870235

checkpoint/CHANGELOG.md

@@ -13,6 +13,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 `AsyncCheckpointer.save()`, and `CheckpointManager.save()`, which saves a custom
 dict of user metadata to `StepMetadata`.
 
+### Fixed
+
+- Add a check to prevent zero-sized arrays from being saved. This behavior
+already resulted in an error, but it was one that was difficult to parse.
+
 ## [0.11.1] - 2025-01-28
 
 ### Changed

checkpoint/orbax/checkpoint/_src/handlers/pytree_checkpoint_handler_test_utils.py

@@ -2308,3 +2308,14 @@ def deserialize(
           checkpoint_handler.save(
               self.directory, args=PyTreeSaveArgs(self.pytree)
           )
+
+    @parameterized.parameters((True,), (False,))
+    def test_zero_size_array(self, use_jax_array: bool):
+      arr = np.ones(shape=(0,))
+      mesh = jax.sharding.Mesh(np.array(jax.devices()), axis_names=('x',))
+      pspec = jax.sharding.PartitionSpec()
+      if use_jax_array:
+        arr = test_utils.create_sharded_array(arr, mesh, pspec)
+      tree = [arr]
+      with self.assertRaisesRegex(ValueError, 'zero size'):
+        self.handler.save(self.directory, args=PyTreeSaveArgs(tree))

checkpoint/orbax/checkpoint/_src/serialization/type_handlers.py

@@ -249,6 +249,12 @@ def check_input_arguments(*args):
       raise ValueError('Found input args with mismatched lengths.')
 
 
+def check_array_values(values: Sequence[Union[jax.Array, np.ndarray]]):
+  for v in values:
+    if v.size == 0:
+      raise ValueError('Cannot save arrays with zero size.')
+
+
 async def _validate_params(
     directory: epath.Path,
     ts_context: ts.Context,
@@ -631,6 +637,7 @@ async def serialize(
     """Uses Tensorstore to serialize a numpy array."""
     args = args or [types.SaveArgs()] * len(values)
     check_input_arguments(values, infos, args)
+    check_array_values(values)
     if logging.vlog_is_on(1):
       _print_ts_debug_data(self._metadata_key, infos)
     copied_values = [copy.deepcopy(v) for v in values]
@@ -1102,6 +1109,7 @@ async def serialize(
         )
     args = args or [types.SaveArgs()] * len(values)
     check_input_arguments(values, infos, args)
+    check_array_values(values)
 
     assert all([info.enable_pinned_host_transfer for info in infos]) or all(
         [not info.enable_pinned_host_transfer for info in infos]