228 lines
8.6 KiB
Python
228 lines
8.6 KiB
Python
import logging
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import os
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from dataclasses import dataclass
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from typing import Any, Dict, Optional
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import ray
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from ray._private import ray_constants
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from ray.train._internal.utils import get_address_and_port
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from ray.train._internal.worker_group import WorkerGroup
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from ray.train.backend import Backend, BackendConfig
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from ray.train.constants import (
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DEFAULT_JAX_DISTRIBUTED_SHUTDOWN_TIMEOUT_S,
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JAX_DISTRIBUTED_SHUTDOWN_TIMEOUT_S,
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)
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from ray.train.v2._internal.util import TrainingFramework
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from ray.util import PublicAPI
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from ray.util.tpu import get_tpu_coordinator_env_vars, get_tpu_worker_resources
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logger = logging.getLogger(__name__)
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# JAX multi-slice (megascale) coordination env vars whose values are
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# authoritatively computed by the controller for the current worker group.
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# These must always be overwritten on each worker (even when the underlying
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# TPU node provider has already set them in the pod environment), because
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# stale values from a previous worker group configuration -- e.g. after a
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# slice was preempted and replaced -- would otherwise cause libtpu's
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# megascale topology coordinator to wait for slices that no longer exist
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# and hang TPU initialization.
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_JAX_MULTISLICE_OVERRIDE_KEYS = frozenset(
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{
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"MEGASCALE_COORDINATOR_ADDRESS",
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"MEGASCALE_NUM_SLICES",
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"MEGASCALE_SLICE_ID",
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}
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)
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@PublicAPI(stability="alpha")
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@dataclass
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class JaxConfig(BackendConfig):
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use_tpu: bool = False
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use_gpu: bool = False
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@property
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def backend_cls(self):
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return _JaxBackend
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@property
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def framework(self):
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return TrainingFramework.JAX
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def to_dict(self) -> Dict[str, Any]:
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config_dict = {
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"use_tpu": self.use_tpu,
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"use_gpu": self.use_gpu,
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}
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return config_dict
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def _setup_jax_distributed_environment(
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master_addr_with_port: str,
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num_workers: int,
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index: int,
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use_tpu: bool,
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use_gpu: bool,
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resources_per_worker: dict,
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jax_env_vars: Optional[dict] = None,
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):
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"""Set up distributed Jax training information.
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This function should be called on each worker. It sets JAX environment
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variables and initializes JAX distributed training.
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Args:
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master_addr_with_port: The master address with port for coordination.
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num_workers: Total number of workers.
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index: Index of this worker.
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use_tpu: Whether to configure for TPU. If True and JAX_PLATFORMS is not
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already set, it will be set to "tpu".
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use_gpu: Whether to configure for GPU. If True and JAX_PLATFORMS is not
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already set, it will be set to "cuda".
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resources_per_worker: The resources per worker.
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jax_env_vars: The JAX coordinator env vars to inject for multi-slice.
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Multi-slice coordination keys (``MEGASCALE_*``) always overwrite
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any pre-existing value in the environment; all other keys are
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only set if they are not already present.
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"""
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# Get JAX_PLATFORMS from environment if already set
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jax_platforms = os.environ.get("JAX_PLATFORMS", "").lower()
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if not jax_platforms and use_tpu:
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os.environ["JAX_PLATFORMS"] = "tpu"
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jax_platforms = "tpu"
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if jax_env_vars:
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for k, v in jax_env_vars.items():
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# For multi-slice coordination keys, always override -- the
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# controller's freshly computed value is the source of truth and
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# may differ from what the TPU node provider baked into the pod
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# environment (e.g. after a slice replacement following preemption).
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# For all other keys, respect any pre-existing value.
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if k in _JAX_MULTISLICE_OVERRIDE_KEYS or k not in os.environ:
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os.environ[k] = v
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if not jax_platforms and use_gpu:
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os.environ["JAX_PLATFORMS"] = "cuda"
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jax_platforms = "cuda"
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if "cuda" in jax_platforms.split(","):
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num_gpus_per_worker = resources_per_worker.get("GPU", 0)
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os.environ["CUDA_VISIBLE_DEVICES"] = ",".join(
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str(i) for i in range(num_gpus_per_worker)
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)
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import jax
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jax_platforms_list = jax_platforms.split(",")
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if "tpu" in jax_platforms_list:
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jax.distributed.initialize(master_addr_with_port, num_workers, index)
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logger.info("Initialized JAX distributed on TPU.")
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elif "cuda" in jax_platforms_list:
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if num_gpus_per_worker > 0:
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local_device_ids = list(range(num_gpus_per_worker))
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else:
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local_device_ids = 0
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jax.distributed.initialize(
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master_addr_with_port, num_workers, index, local_device_ids
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)
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logger.info("Initialized JAX distributed on CUDA.")
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elif "cpu" in jax_platforms_list:
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jax.distributed.initialize(master_addr_with_port, num_workers, index)
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logger.info("Initialized JAX distributed on CPU.")
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def _shutdown_jax_distributed():
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"""Shutdown JAX distributed environment.
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This function should be called on each worker during cleanup.
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If JAX distributed was not initialized, this is a no-op.
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"""
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try:
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import jax
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jax.distributed.shutdown()
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except Exception as e:
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logger.warning(f"Error during JAX distributed shutdown: {e}")
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class _JaxBackend(Backend):
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def on_start(self, worker_group: WorkerGroup, backend_config: JaxConfig):
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if not backend_config.use_tpu and not backend_config.use_gpu:
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return
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master_addr, master_port = worker_group.execute_single(0, get_address_and_port)
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master_addr_with_port = f"{master_addr}:{master_port}"
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if backend_config.use_tpu and hasattr(worker_group, "get_worker_group_context"):
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num_slices = worker_group.get_worker_group_context().num_slices
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else:
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num_slices = 1
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# Calculate the number of workers per slice for multi-slice env setup.
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if backend_config.use_tpu and num_slices > 1:
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# Handle the case where a user requests less workers than the total
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# capacity of the TPU slice.
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scaling_config = worker_group._train_run_context.scaling_config
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workers_per_slice, _ = get_tpu_worker_resources(
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topology=scaling_config.topology,
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accelerator_type=scaling_config.accelerator_type,
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resources_per_unit=scaling_config.resources_per_worker,
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num_slices=1,
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)
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else:
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# Assume even distribution based on the requested number of workers.
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workers_per_slice = max(1, len(worker_group) // num_slices)
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# Set up JAX distributed environment on all workers
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num_workers_total = len(worker_group)
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setup_futures = []
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for i in range(num_workers_total):
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env_vars = {}
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if num_slices > 1:
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slice_id = min(i // workers_per_slice, num_slices - 1)
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env_vars = get_tpu_coordinator_env_vars(
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coordinator_address=master_addr,
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num_slices=num_slices,
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slice_id=slice_id,
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)
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setup_futures.append(
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worker_group.execute_single_async(
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i,
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_setup_jax_distributed_environment,
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master_addr_with_port=master_addr_with_port,
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num_workers=len(worker_group),
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index=i,
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use_tpu=backend_config.use_tpu,
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use_gpu=backend_config.use_gpu,
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resources_per_worker=worker_group.get_resources_per_worker(),
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jax_env_vars=env_vars,
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)
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)
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ray.get(setup_futures)
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def on_shutdown(self, worker_group: WorkerGroup, backend_config: JaxConfig):
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"""Cleanup JAX distributed resources when shutting down worker group."""
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if not backend_config.use_tpu and not backend_config.use_gpu:
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return
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# Shutdown JAX distributed on all workers
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shutdown_futures = worker_group.execute_async(_shutdown_jax_distributed)
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timeout_s = ray_constants.env_integer(
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JAX_DISTRIBUTED_SHUTDOWN_TIMEOUT_S,
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DEFAULT_JAX_DISTRIBUTED_SHUTDOWN_TIMEOUT_S,
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)
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try:
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ray.get(shutdown_futures, timeout=timeout_s)
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logger.debug("JAX distributed shutdown completed")
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except ray.exceptions.GetTimeoutError:
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logger.warning(
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f"JAX distributed shutdown timed out after {timeout_s} seconds. "
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"This may indicate workers are hung or unresponsive."
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)
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except Exception as e:
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logger.warning(f"Error during JAX distributed shutdown: {e}")
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