2025-08-11 12:24:21 +08:00

129 lines
5.7 KiB
Python

# Copyright 2022 The JAX Authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from __future__ import annotations
from collections.abc import Sequence
import logging
from jax._src.cloud_tpu_init import running_in_cloud_tpu_vm
logger = logging.getLogger(__name__)
class ClusterEnv:
"""Interface for defining a cluster environment.
To enable auto bootstrapping (aka :func:`jax.distributed.initialize()`),
cluster environments need to derive from :class:`ClusterEnv` and implement
:func:`is_env_present`, :func:`get_coordinator_address`,
:func:`get_process_count`, and :func:`get_process_id`.
:class:`ClusterEnv` subclasses are automatically detected when imported.
"""
_cluster_types: list[type[ClusterEnv]] = []
opt_in_only_method: bool = False # Override this in derived classes if necessary
def __init_subclass__(cls, **kwargs):
super().__init_subclass__(**kwargs)
cls._cluster_types.append(cls)
@classmethod
# pytype: disable=bad-return-type
def auto_detect_unset_distributed_params(cls,
coordinator_address: str | None,
num_processes: int | None,
process_id: int | None,
local_device_ids: Sequence[int] | None,
cluster_detection_method: str | None,
initialization_timeout: int | None,
) -> tuple[str | None, int | None, int | None,
Sequence[int] | None]:
# First, we check the spec detection method because it will ignore submitted values
# If if succeeds.
if cluster_detection_method is not None:
env = next( (env for env in cls._cluster_types if env.name == cluster_detection_method), None ) # pytype: disable=attribute-error
if env is None:
logger.error(f"Automatic Distributed initialization can not proceed:"
f" {cluster_detection_method} is not supported.")
elif not env.is_env_present():
logger.error(f"Automatic Distributed initialization can not proceed:"
f" {cluster_detection_method} is supported but not functional in this environment.")
else:
env = next((env for env in cls._cluster_types if env.opt_in_only_method == False and env.is_env_present()), None)
# Above: I have wrapped the env selection in a conditional to go through
# opt-in methods first (currently only mpi4py) but to check all possible options
# otherwise. Passing no cluster_detection_method results in the default, original behavior.
if env:
logger.debug('Initializing distributed JAX environment via %s', env.__name__)
if coordinator_address is None:
coordinator_address = env.get_coordinator_address(timeout_secs=initialization_timeout)
if num_processes is None:
num_processes = env.get_process_count()
if process_id is None:
process_id = env.get_process_id()
# Never automatically set local_device_ids on TPUs
# Defaults to single process per device if local_process_id is available.
# This only runs if we're in a managed distributed environment.
# Otherwise local_device_ids will remain unset,
# which will default to all devices being visible.
if (local_device_ids is None and not running_in_cloud_tpu_vm and
env.get_local_process_id() is not None):
local_device_ids = [env.get_local_process_id()] # type: ignore[list-item]
else:
logger.debug('Could not find a known environment for initializing distributed JAX. '
'Known environments: %s', ', '.join(e.__name__ for e in cls._cluster_types))
return (coordinator_address, num_processes, process_id, local_device_ids)
# pytype: enable=bad-return-type
@classmethod
def is_env_present(cls) -> bool:
"""Returns True if process is running in this cluster environment.
"""
raise NotImplementedError("ClusterEnv subclasses must implement is_env_present")
@classmethod
def get_coordinator_address(cls, timeout_secs: int | None) -> str:
"""Returns address and port used by JAX to bootstrap.
Process id 0 will open a tcp socket at "hostname:port" where
all the processes will connect to initialize the distributed JAX service.
The selected port needs to be free.
:func:`get_coordinator_address` needs to return the same hostname and port on all the processes.
Returns:
"hostname:port"
"""
raise NotImplementedError("ClusterEnv subclasses must implement get_coordinator_address")
@classmethod
def get_process_count(cls) -> int:
raise NotImplementedError("ClusterEnv subclasses must implement get_process_count")
@classmethod
def get_process_id(cls) -> int:
raise NotImplementedError("ClusterEnv subclasses must implement get_process_id")
@classmethod
def get_local_process_id(cls) -> int | None:
""" Get index of current process inside a host.
The method is only useful to support single device per process.
In that case, each process will see a local device whose ID is
the same as its local process ID.
If None, JAX will not restrict the visible devices.
"""
return None