Files
2026-07-13 13:17:40 +08:00

243 lines
8.3 KiB
Python

import os
import sys
import time
from pathlib import Path
from typing import List
import pytest
import ray
import ray.train
from ray._common.test_utils import wait_for_condition
from ray.cluster_utils import Cluster
from ray.train.tests.util import create_dict_checkpoint, load_dict_checkpoint
from ray.train.v2._internal.constants import HEALTH_CHECK_INTERVAL_S_ENV_VAR
from ray.train.v2.jax import JaxTrainer
@pytest.fixture
def cluster():
cluster = Cluster(initialize_head=True, head_node_args=dict(num_cpus=0))
cluster.wait_for_nodes()
ray.init(
address=cluster.address,
runtime_env={"working_dir": str(Path(__file__).parent)},
)
yield cluster
ray.shutdown()
cluster.shutdown()
def train_fn(config: dict):
train_context = ray.train.get_context()
rank = train_context.get_world_rank()
start_epoch = 1
checkpoint = ray.train.get_checkpoint()
min_world_size = None
max_world_size = None
if checkpoint:
checkpoint_data = load_dict_checkpoint(checkpoint)
start_epoch = checkpoint_data["epoch"] + 1
min_world_size = checkpoint_data.get("min_world_size")
max_world_size = checkpoint_data.get("max_world_size")
if rank == 0:
print("Restoring from epoch: ", start_epoch)
for epoch in range(start_epoch, config.get("num_epochs", 60) + 1):
world_size = train_context.get_world_size()
if min_world_size is None:
min_world_size = world_size
if max_world_size is None:
max_world_size = world_size
min_world_size = min(min_world_size, world_size)
max_world_size = max(max_world_size, world_size)
# TODO: This test injects errors by "killing nodes," which ungracefully
# kills processes. This means that any backlog in the checkpoint queue
# will not be flushed to the controller.
# This means that the checkpoint populated on restore may not be
# the most recent one.
# Set the poll interval < health check interval to reduce the
# backlog size to mitigate the issue.
time.sleep(2 * config.get("health_check_interval_s", 1))
with create_dict_checkpoint(
{
"epoch": epoch,
"min_world_size": min_world_size,
"max_world_size": max_world_size,
}
) as checkpoint:
ray.train.report(
{
"epoch": epoch,
"world_size": world_size,
"min_world_size": min_world_size,
"max_world_size": max_world_size,
},
checkpoint=checkpoint if rank == 0 else None,
checkpoint_dir_name=f"checkpoint-epoch={epoch}",
)
if rank == 0:
print("Finished epoch: ", epoch)
@pytest.mark.skipif(
sys.version_info >= (3, 12),
reason="Current jax version (0.4.13) is not supported in python 3.12+",
)
def test_elastic_training_tpu(monkeypatch, tmp_path, cluster):
"""End to end test for TPU elastic training with the JaxTrainer."""
unit_time_s = 1.0
health_check_interval_s = unit_time_s
elastic_resize_monitor_interval_s = unit_time_s * 5
num_epochs = 30
monkeypatch.setenv(HEALTH_CHECK_INTERVAL_S_ENV_VAR, str(health_check_interval_s))
monkeypatch.setenv("JAX_PLATFORMS", "cpu")
@ray.remote(num_cpus=0)
def run_training():
trainer = JaxTrainer(
train_fn,
train_loop_config={
"num_epochs": num_epochs,
"health_check_interval_s": health_check_interval_s,
},
scaling_config=ray.train.ScalingConfig(
use_tpu=True,
accelerator_type="TPU-V6E",
topology="2x4",
resources_per_worker={"TPU": 4, "CPU": 1},
num_workers=(2, 6), # Scale between 1 and 3 slices.
elastic_resize_monitor_interval_s=elastic_resize_monitor_interval_s,
),
run_config=ray.train.RunConfig(
storage_path=str(tmp_path),
checkpoint_config=ray.train.CheckpointConfig(num_to_keep=2),
failure_config=ray.train.FailureConfig(max_failures=3),
),
)
return trainer.fit()
run_training_future = run_training.remote()
start = time.time()
ALL_NODES = []
def print_status(message):
elapsed = time.time() - start
print(f"\n{'-' * 80}")
cluster_resources = {
resource: value
for resource, value in ray.cluster_resources().items()
if "TPU" in resource or "CPU" in resource
}
print(f"[elapsed={elapsed:.1f}s] {cluster_resources=}")
print(message)
print(f"{'-' * 80}\n")
def provision_tpu_node(slice_name: str, worker_id: int, is_head: bool = False):
pod_type = "v6e-8"
topology = "2x4"
node_env = {
"PATH": os.environ.get("PATH", ""),
"TPU_NAME": slice_name,
"TPU_WORKER_ID": str(worker_id),
"TPU_ACCELERATOR_TYPE": pod_type,
"TPU_TOPOLOGY": topology,
"JAX_PLATFORMS": "cpu",
HEALTH_CHECK_INTERVAL_S_ENV_VAR: str(health_check_interval_s),
}
labels = {
"ray.io/tpu-slice-name": slice_name,
"ray.io/tpu-worker-id": str(worker_id),
"ray.io/tpu-pod-type": pod_type,
}
resources = {"TPU": 4, "accelerator_type:TPU-V6E": 1}
if is_head:
resources[f"TPU-{pod_type}-head"] = 1
node = cluster.add_node(
num_cpus=8,
resources=resources,
labels=labels,
env_vars=node_env,
wait=True,
)
return node
def verify_active_workers(expected_count: int) -> bool:
try:
from ray.util.state import list_actors
workers = list_actors(
filters=[("class_name", "=", "RayTrainWorker"), ("state", "=", "ALIVE")]
)
return len(workers) == expected_count
except Exception:
# Ignore transient State API errors during cluster churn
return False
def remove_nodes(nodes: List):
for node in nodes:
cluster.remove_node(node)
cluster.wait_for_nodes()
print_status(f"Removed {len(nodes)} node(s).")
print_status(
"Adding 1 TPU node. Waiting for training to ignore it since it's not a full slice."
)
ALL_NODES.append(
provision_tpu_node(slice_name="slice-A", worker_id=0, is_head=True)
)
print_status("Adding 2nd TPU node to complete slice-A. Training should start.")
ALL_NODES.append(
provision_tpu_node(slice_name="slice-A", worker_id=1, is_head=False)
)
print_status("Waiting for initial scale-up to 2 workers...")
wait_for_condition(lambda: verify_active_workers(2), timeout=120)
print_status("Adding full second TPU slice. Policy should upscale.")
ALL_NODES.append(
provision_tpu_node(slice_name="slice-B", worker_id=0, is_head=True)
)
ALL_NODES.append(
provision_tpu_node(slice_name="slice-B", worker_id=1, is_head=False)
)
print_status("Waiting for elastic scale-up to 4 workers.")
wait_for_condition(lambda: verify_active_workers(4), timeout=120)
# Run a couple of epochs at max capacity so the metrics reflect the max_world_size.
time.sleep(8)
# Multi-host TPUs on GKE with KubeRay are scaled atomically in slices.
print_status("Killing second TPU slice to simulate full slice preemption.")
node_b_worker = ALL_NODES.pop()
node_b_head = ALL_NODES.pop()
remove_nodes([node_b_worker, node_b_head])
print_status("Waiting for policy to scale down and recover with 2 workers.")
wait_for_condition(lambda: verify_active_workers(2), timeout=120)
# Run a couple of epochs after the recovery.
time.sleep(8)
result: ray.train.Result = ray.get(run_training_future)
print_status(f"Training finished with result: {result}")
assert not result.error
assert result.metrics["min_world_size"] == 2
assert result.metrics["max_world_size"] == 4
assert result.checkpoint
assert Path(result.checkpoint.path).name == f"checkpoint-epoch={num_epochs}"
if __name__ == "__main__":
sys.exit(pytest.main(["-v", "-x", __file__]))