# 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_bind_address: str | None = None): 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, initialization_timeout, ) ) 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 # The default value of [::]:port tells the coordinator to bind to all # available addresses on the same port as coordinator_address. default_coordinator_bind_address = '[::]:' + coordinator_address.rsplit(':', 1)[1] coordinator_bind_address = (coordinator_bind_address or os.environ.get('JAX_COORDINATOR_BIND_ADDRESS', default_coordinator_bind_address)) if coordinator_bind_address is None: raise ValueError('coordinator_bind_address should be defined.') if local_device_ids: visible_devices = ','.join(str(x) for x in local_device_ids) 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_bind_address ) self.service = xla_extension.get_distributed_runtime_service( coordinator_bind_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() 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, coordinator_bind_address: str | None = None): """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. coordinator_bind_address: the address and port to which the coordinator service on process `0` should bind. If this is not specified, the default is to bind to all available addresses on the same port as ``coordinator_address``. On systems that have multiple network interfaces per node it may be insufficient to only have the coordinator service listen on one address/interface. Raises: RuntimeError: If :func:`~jax.distributed.initialize` is called more than once or if called after the backend is already initialized. 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, coordinator_bind_address) atexit.register(shutdown) def shutdown(): """Shuts down the distributed system. Does nothing if the distributed system is not running.""" global_state.shutdown()