Source code for jax._src.distributed

# Copyright 2021 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

import atexit
from collections.abc import Sequence
import logging
import os
from typing import Any

from jax._src import clusters
from jax._src import config
from jax._src import xla_bridge
from jax._src.lib import xla_extension

logger = logging.getLogger(__name__)


class State:
  process_id: int = 0
  num_processes: int = 1
  service: Any | None = None
  client: Any | None = None
  preemption_sync_manager: Any | None = None
  coordinator_address: str | None = None

  def initialize(self,
                 coordinator_address: str | None = None,
                 num_processes: int | None = None,
                 process_id: int | None = None,
                 local_device_ids: int | Sequence[int] | None = None,
                 initialization_timeout: int = 300):
    coordinator_address = (coordinator_address or
                           os.environ.get('JAX_COORDINATOR_ADDRESS', None))
    if isinstance(local_device_ids, int):
      local_device_ids = [local_device_ids]

    (coordinator_address, num_processes, process_id, local_device_ids) = (
        clusters.ClusterEnv.auto_detect_unset_distributed_params(
            coordinator_address, num_processes, process_id, local_device_ids
        )
    )

    if coordinator_address is None:
      raise ValueError('coordinator_address should be defined.')
    if num_processes is None:
      raise ValueError('Number of processes must be defined.')
    if process_id is None:
      raise ValueError('The process id of the current process must be defined.')

    self.coordinator_address = coordinator_address

    if local_device_ids:
      visible_devices = ','.join(str(x) for x in local_device_ids) # type: ignore[union-attr]
      logger.info('JAX distributed initialized with visible devices: %s', visible_devices)
      config.update("jax_cuda_visible_devices", visible_devices)
      config.update("jax_rocm_visible_devices", visible_devices)

    self.process_id = process_id

    if process_id == 0:
      if self.service is not None:
        raise RuntimeError('distributed.initialize should only be called once.')
      logger.info('Starting JAX distributed service on %s', coordinator_address)
      self.service = xla_extension.get_distributed_runtime_service(
          coordinator_address, num_processes)

    self.num_processes = num_processes

    if self.client is not None:
      raise RuntimeError('distributed.initialize should only be called once.')

    self.client = xla_extension.get_distributed_runtime_client(
        coordinator_address, process_id, init_timeout=initialization_timeout)
    logger.info('Connecting to JAX distributed service on %s', coordinator_address)
    self.client.connect()

    self.initialize_preemption_sync_manager()

  def shutdown(self):
    if self.client:
      self.client.shutdown()
      self.client = None
    if self.service:
      self.service.shutdown()
      self.service = None
    if self.preemption_sync_manager:
      self.preemption_sync_manager = None

  def initialize_preemption_sync_manager(self):
    if self.preemption_sync_manager is not None:
      raise RuntimeError(
          'Preemption sync manager should only be initialized once.')
    self.preemption_sync_manager = (
        xla_extension.create_preemption_sync_manager())
    self.preemption_sync_manager.initialize(self.client)

global_state = State()


[docs] def initialize(coordinator_address: str | None = None, num_processes: int | None = None, process_id: int | None = None, local_device_ids: int | Sequence[int] | None = None, initialization_timeout: int = 300): """Initializes the JAX distributed system. Calling :func:`~jax.distributed.initialize` prepares JAX for execution on multi-host GPU and Cloud TPU. :func:`~jax.distributed.initialize` must be called before performing any JAX computations. The JAX distributed system serves a number of roles: * it allows JAX processes to discover each other and share topology information, * it performs health checking, ensuring that all processes shut down if any process dies, and * it is used for distributed checkpointing. If you are using TPU, Slurm, or Open MPI, all arguments are optional: if omitted, they will be chosen automatically. Otherwise, you must provide the ``coordinator_address``, ``num_processes``, and ``process_id`` arguments to :func:`~jax.distributed.initialize`. Args: coordinator_address: the IP address of process `0` and a port on which that process should launch a coordinator service. The choice of port does not matter, so long as the port is available on the coordinator and all processes agree on the port. May be ``None`` only on supported environments, in which case it will be chosen automatically. Note that special addresses like ``localhost`` or ``127.0.0.1`` usually mean that the program will bind to a local interface and are not suitable when running in a multi-host environment. num_processes: Number of processes. May be ``None`` only on supported environments, in which case it will be chosen automatically. process_id: The ID number of the current process. The ``process_id`` values across the cluster must be a dense range ``0``, ``1``, ..., ``num_processes - 1``. May be ``None`` only on supported environments; if ``None`` it will be chosen automatically. local_device_ids: Restricts the visible devices of the current process to ``local_device_ids``. If ``None``, defaults to all local devices being visible to the process except when processes are launched via Slurm and Open MPI on GPUs. In that case, it will default to a single device per process. initialization_timeout: Time period (in seconds) for which connection will be retried. If the initialization takes more than the timeout specified, the initialization will error. Defaults to 300 secs i.e. 5 mins. Raises: RuntimeError: If :func:`~jax.distributed.initialize` is called more than once. Example: Suppose there are two GPU processes, and process 0 is the designated coordinator with address ``10.0.0.1:1234``. To initialize the GPU cluster, run the following commands before anything else. On process 0: >>> jax.distributed.initialize(coordinator_address='10.0.0.1:1234', num_processes=2, process_id=0) # doctest: +SKIP On process 1: >>> jax.distributed.initialize(coordinator_address='10.0.0.1:1234', num_processes=2, process_id=1) # doctest: +SKIP """ if xla_bridge.backends_are_initialized(): raise RuntimeError("jax.distributed.initialize() must be called before " "any JAX computations are executed.") global_state.initialize(coordinator_address, num_processes, process_id, local_device_ids, initialization_timeout) atexit.register(shutdown)
[docs] def shutdown(): """Shuts down the distributed system. Does nothing if the distributed system is not running.""" global_state.shutdown()