Update

Author: Micky774

jax/_src/array.py

@@ -404,11 +404,27 @@ def __array__(self, dtype=None, context=None, copy=None):
  kwds = {} if copy is None else {'copy': copy}
  return np.asarray(self._value, dtype=dtype, **kwds)
 
- def __dlpack__(self, *, stream: int | Any | None = None):
+ def __dlpack__(self, *, stream: int | Any | None = None,
+ max_version: tuple[int, int] | None = None,
+ dl_device: tuple[enum.Enum, int] | None = None,
+ copy: bool | None = None):
  if len(self._arrays) != 1:
  raise BufferError("__dlpack__ only supported for unsharded arrays.")
  from jax._src.dlpack import to_dlpack # pylint: disable=g-import-not-at-top
- return to_dlpack(self, stream=stream)
+
+ device_set = self.sharding.device_set
+ if len(device_set) > 1:
+ raise BufferError(
+ "to_dlpack can only pack a dlpack tensor from an array on a singular "
+ f"device, but an array with a Sharding over {len(device_set)} devices "
+ "was provided."
+ )
+ device = device_set.pop()
+ return to_dlpack(self, stream=stream,
+ max_version=max_version,
+ device=device,
+ dl_device=dl_device, # type: ignore
+ copy=copy)
 
  def __dlpack_device__(self) -> tuple[enum.Enum, int]:
  if len(self._arrays) != 1:

jax/_src/dlpack.py

@@ -24,7 +24,10 @@
 from jax._src.lib import xla_client
 from jax._src.lib import xla_extension_version
 from jax._src.typing import Array
+from jax._src.api import device_put
 
+DLPACK_VERSION = (0, 1)
+MIN_DLPACK_VERSION = (0, 1)
 
 # A set of dtypes that dlpack supports.
 # Note: Make sure to use a "type", not a dtype instance, when looking up this set
@@ -48,9 +51,33 @@ class DLDeviceType(enum.IntEnum):
  kDLCUDA = 2
  kDLROCM = 10
 
+def _to_dlpack(x: Array, stream: int | Any | None,
+ device: xla_client.Device | None = None,
+ dlpack_device: xla_client.Device | None = None,
+ copy: bool | None = None):
+ arr = None
+ if dlpack_device and dlpack_device != device:
+ if copy is not None and not copy:
+ raise ValueError(
+ f"Specified {dlpack_device=} which requires a copy since the source device "
+ f"is {repr(device)}, however copy=False. Set copy=True or "
+ "copy=None to perform the requested operation."
+ )
+ else:
+ arr = device_put(x, dlpack_device)
+ if arr is None:
+ arr = x.copy() if copy else x
+
+ return xla_client._xla.buffer_to_dlpack_managed_tensor(
+ arr.addressable_data(0), stream=stream
+ ) # type: ignore
 
 def to_dlpack(x: Array, take_ownership: bool = False,
- stream: int | Any | None = None):
+ stream: int | Any | None = None,
+ device: xla_client.Device | None = None,
+ dl_device: tuple[DLDeviceType, int] | None = None,
+ max_version: tuple[int, int] | None = None,
+ copy : bool | None = None):
  """Returns a DLPack tensor that encapsulates a :class:`~jax.Array` ``x``.
 
  Args:
@@ -73,14 +100,40 @@ def to_dlpack(x: Array, take_ownership: bool = False,
  if not isinstance(x, array.ArrayImpl):
  raise TypeError("Argument to to_dlpack must be a jax.Array, "
  f"got {type(x)}")
- assert len(x.devices()) == 1
  if take_ownership:
  warnings.warn(
  "take_ownership in to_dlpack is deprecated and it is a no-op."
  )
- return xla_client._xla.buffer_to_dlpack_managed_tensor(
- x.addressable_data(0), stream=stream
- ) # type: ignore
+
+ dlpack_device = None
+ dl_device_type, local_hardware_id = dl_device if dl_device else (None, None)
+ if dl_device_type:
+ try:
+ dl_device_platform = {
+ DLDeviceType.kDLCPU: "cpu",
+ DLDeviceType.kDLCUDA: "cuda",
+ DLDeviceType.kDLROCM: "rocm",
+ }[dl_device_type]
+ backend = xla_bridge.get_backend(dl_device_platform)
+ dlpack_device = backend.device_from_local_hardware_id(local_hardware_id)
+ except TypeError:
+ # https://data-apis.org/array-api/latest/API_specification/generated/array_api.array.__dlpack__.html
+ # recommends using BufferError.
+ raise BufferError(
+ "The device specification passed to to_dlpack contains an unsupported "
+ f"device type (DLDeviceType: {dl_device_type})")
+
+ if max_version is None or max_version[0] >= DLPACK_VERSION[0]:
+ return _to_dlpack(x, stream=stream, device=device, dlpack_device=dlpack_device, copy=copy)
+ elif max_version >= MIN_DLPACK_VERSION:
+ # Legacy path to be implemented when XLA adopts DLManagedTensorVersioned format
+ raise RuntimeError("This branch should be unreachable. "
+ "Please open a bug if you see this.")
+ else:
+ raise BufferError(
+ f"JAX does not support any version below {MIN_DLPACK_VERSION} but "
+ f"version ({max_version}) was requested."
+ )
 
 
 def from_dlpack(external_array):