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sglang/test/registered/unit/managers/test_data_parallel_controller.py
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"""DPBudget + DataParallelController dispatch tests.
The e2e counterpart, over the real scheduler load-report path, is
test/registered/disaggregation/test_disaggregation_dp_attention.py.
Fragility: scheduler tests bypass `DataParallelController.__init__` via
`__new__` and inject only the attrs the schedulers read (`workers`, `status`,
`_active_workers`, `round_robin_counter`, `dp_budget`). Update `_make_controller`
if a scheduler starts reading another attr. `maybe_external_dp_rank_routing`
is exercised as the real method, no mock. The refresh-throttle tests inject
`load_snapshot_reader` and `_last_refresh_time` on top of those.
"""
import time
import unittest
from types import SimpleNamespace
from unittest.mock import MagicMock
import msgspec.structs
from sglang.test.ci.ci_register import register_cpu_ci
from sglang.test.test_utils import CustomTestCase, maybe_stub_sgl_kernel
maybe_stub_sgl_kernel()
from sglang.srt.managers.data_parallel_controller import (
DataParallelController,
DPBudget,
LoadBalanceMethod,
)
from sglang.srt.managers.load_snapshot import LoadSnapshot
register_cpu_ci(est_time=12, suite="base-a-test-cpu")
_BASE_LOAD = msgspec.structs.replace(
LoadSnapshot(dp_rank=0),
max_total_num_tokens=4096,
max_running_requests=128,
)
def _load(**overrides) -> LoadSnapshot:
return msgspec.structs.replace(_BASE_LOAD, **overrides)
def _make_controller(dp_size: int) -> DataParallelController:
"""Bypass __init__; inject only the attrs dispatch methods read."""
ctl = DataParallelController.__new__(DataParallelController)
ctl.workers = [MagicMock(name=f"worker_{i}") for i in range(dp_size)]
ctl.status = [True] * dp_size
ctl._active_workers = list(range(dp_size))
ctl.round_robin_counter = 0
ctl.dp_budget = DPBudget(dp_size=dp_size)
return ctl
def _req(routed_dp_rank=None, bootstrap_room=None, input_ids=None):
"""Req stand-in; SimpleNamespace avoids pinning to the Req dataclass schema."""
return SimpleNamespace(
routed_dp_rank=routed_dp_rank,
bootstrap_room=bootstrap_room,
input_ids=input_ids or [],
)
class TestDPBudgetUpdateBudget(CustomTestCase):
def test_maps_running_plus_waiting_to_total_requests(self):
budget = DPBudget(dp_size=2)
budget.update_budget(
[
_load(dp_rank=0, timestamp=1.0, num_running_reqs=3, num_waiting_reqs=2),
_load(dp_rank=1, timestamp=1.0, num_running_reqs=5, num_waiting_reqs=1),
]
)
self.assertEqual(budget.total_requests, [5, 6])
def test_maps_num_total_tokens_not_num_used_tokens(self):
budget = DPBudget(dp_size=2)
budget.update_budget(
[
_load(
dp_rank=0, timestamp=1.0, num_used_tokens=100, num_total_tokens=150
),
_load(
dp_rank=1, timestamp=1.0, num_used_tokens=80, num_total_tokens=80
),
]
)
self.assertEqual(budget.total_tokens, [150, 80])
def test_partial_update_only_affects_reported_rank(self):
budget = DPBudget(dp_size=3)
budget.update_budget(
[
_load(
dp_rank=0, timestamp=1.0, num_running_reqs=10, num_total_tokens=100
),
_load(
dp_rank=1, timestamp=1.0, num_running_reqs=20, num_total_tokens=200
),
_load(
dp_rank=2, timestamp=1.0, num_running_reqs=30, num_total_tokens=300
),
]
)
budget.update_budget(
[
_load(
dp_rank=1,
timestamp=2.0,
num_running_reqs=1,
num_waiting_reqs=1,
num_total_tokens=50,
)
]
)
self.assertEqual(budget.total_requests, [10, 2, 30])
self.assertEqual(budget.total_tokens, [100, 50, 300])
class TestDPBudgetDispatch(CustomTestCase):
"""DPBudget.dispatch picks a rank from current state and updates counters."""
def test_total_requests_dispatch_picks_min_and_increments(self):
budget = DPBudget(dp_size=3)
budget.total_requests = [4, 2, 7]
rank = budget.dispatch(LoadBalanceMethod.TOTAL_REQUESTS)
self.assertEqual(rank, 1)
self.assertEqual(
budget.total_requests[1],
3,
"dispatch should increment chosen worker's request count",
)
def test_total_tokens_dispatch_applies_estimated_tokens(self):
budget = DPBudget(dp_size=3)
budget.total_tokens = [100, 50, 200]
budget.total_requests = [0, 0, 0]
rank = budget.dispatch(LoadBalanceMethod.TOTAL_TOKENS, estimated_tokens=30)
self.assertEqual(rank, 1, "should pick worker with min total_tokens")
self.assertEqual(
budget.total_tokens[1],
80,
"dispatch should add estimated_tokens to chosen worker",
)
self.assertEqual(
budget.total_requests[1],
1,
"dispatch should also increment request count",
)
def test_total_tokens_tie_breaks_on_total_requests(self):
budget = DPBudget(dp_size=3)
budget.total_tokens = [50, 50, 50]
budget.total_requests = [4, 2, 7]
rank = budget.dispatch(LoadBalanceMethod.TOTAL_TOKENS, estimated_tokens=10)
self.assertEqual(
rank, 1, "tie on total_tokens should fall back to min total_requests"
)
def test_dispatch_returns_none_for_methods_not_handled(self):
"""Round-robin and follow_bootstrap_room dispatch elsewhere; DPBudget
only handles the load-aware variants."""
budget = DPBudget(dp_size=3)
self.assertIsNone(budget.dispatch(LoadBalanceMethod.ROUND_ROBIN))
self.assertIsNone(budget.dispatch(LoadBalanceMethod.FOLLOW_BOOTSTRAP_ROOM))
class TestRoundRobinScheduler(CustomTestCase):
def test_cycles_through_active_workers_in_order(self):
ctl = _make_controller(dp_size=4)
for _ in range(8):
ctl.round_robin_scheduler(_req())
# 8 reqs across 4 active workers — 2 each, in round-robin order
for i, worker in enumerate(ctl.workers):
self.assertEqual(worker.send_pyobj.call_count, 2, f"worker {i} call count")
def test_first_dispatch_picks_worker_zero(self):
ctl = _make_controller(dp_size=4)
ctl.round_robin_scheduler(_req())
ctl.workers[0].send_pyobj.assert_called_once()
for i in (1, 2, 3):
ctl.workers[i].send_pyobj.assert_not_called()
def test_skips_inactive_workers(self):
ctl = _make_controller(dp_size=4)
ctl.status[1] = False
ctl.status[3] = False
for _ in range(6):
ctl.round_robin_scheduler(_req())
# Only workers 0 and 2 are active — should split 6 reqs evenly
self.assertEqual(ctl.workers[0].send_pyobj.call_count, 3)
ctl.workers[1].send_pyobj.assert_not_called()
self.assertEqual(ctl.workers[2].send_pyobj.call_count, 3)
ctl.workers[3].send_pyobj.assert_not_called()
def test_routed_dp_rank_bypasses_counter(self):
"""External dp-rank routing must not advance the counter."""
ctl = _make_controller(dp_size=4)
ctl.round_robin_scheduler(_req(routed_dp_rank=2))
ctl.workers[2].send_pyobj.assert_called_once()
self.assertEqual(
ctl.round_robin_counter,
0,
"external routing must not advance the round-robin counter",
)
# Subsequent round-robin req still lands on worker 0
ctl.round_robin_scheduler(_req())
ctl.workers[0].send_pyobj.assert_called_once()
class TestFollowBootstrapRoomScheduler(CustomTestCase):
def test_dispatches_by_bootstrap_room_modulo(self):
ctl = _make_controller(dp_size=4)
for room, expected_rank in [
(0, 0),
(1, 1),
(4, 0),
(5, 1),
(100, 0),
(101, 1),
]:
ctl.follow_bootstrap_room_scheduler(_req(bootstrap_room=room))
ctl.workers[expected_rank].send_pyobj.assert_called()
def test_requires_bootstrap_room(self):
ctl = _make_controller(dp_size=4)
with self.assertRaises(AssertionError):
ctl.follow_bootstrap_room_scheduler(_req(bootstrap_room=None))
def test_routed_dp_rank_bypasses_bootstrap_room(self):
ctl = _make_controller(dp_size=4)
ctl.follow_bootstrap_room_scheduler(_req(routed_dp_rank=3, bootstrap_room=1))
ctl.workers[3].send_pyobj.assert_called_once()
ctl.workers[1].send_pyobj.assert_not_called()
class TestTotalRequestsScheduler(CustomTestCase):
def test_dispatches_to_min_request_worker(self):
ctl = _make_controller(dp_size=4)
ctl.dp_budget.total_requests = [5, 3, 1, 4]
ctl.total_requests_scheduler(_req())
ctl.workers[2].send_pyobj.assert_called_once()
for i in (0, 1, 3):
ctl.workers[i].send_pyobj.assert_not_called()
self.assertEqual(
ctl.dp_budget.total_requests[2],
2,
"DPBudget must record the dispatch by incrementing the counter",
)
def test_routed_dp_rank_bypasses_budget(self):
ctl = _make_controller(dp_size=4)
ctl.dp_budget.total_requests = [5, 3, 1, 4]
ctl.total_requests_scheduler(_req(routed_dp_rank=0))
ctl.workers[0].send_pyobj.assert_called_once()
# DPBudget must not be touched when bypassed
self.assertEqual(
ctl.dp_budget.total_requests,
[5, 3, 1, 4],
"external routing must not mutate DPBudget state",
)
class TestStatusAwarenessInconsistency(CustomTestCase):
"""Document a divergence: ``round_robin_scheduler`` skips workers whose
``status`` is False, but ``total_requests_scheduler`` /
``total_tokens_scheduler`` route purely by DPBudget — they do NOT
consult ``self.status``. If a future change unifies this behaviour,
this test will fail and force a reviewer to confirm intent."""
def test_total_requests_ignores_status(self):
ctl = _make_controller(dp_size=4)
# Worker 2 is the global minimum AND marked inactive.
ctl.dp_budget.total_requests = [5, 3, 1, 4]
ctl.status[2] = False
ctl.total_requests_scheduler(_req())
# Current behaviour: still dispatches to the inactive worker.
ctl.workers[2].send_pyobj.assert_called_once()
class TestRefreshLoadBudgetThrottle(CustomTestCase):
@staticmethod
def _controller_with_reader(dp_size, snapshots):
ctl = _make_controller(dp_size)
ctl.load_snapshot_reader = MagicMock()
ctl.load_snapshot_reader.read_all.return_value = snapshots
return ctl
def test_throttled_refresh_spreads_a_burst_across_ranks(self):
idle = [_load(dp_rank=i, timestamp=1.0, num_total_tokens=0) for i in range(4)]
ctl = self._controller_with_reader(dp_size=4, snapshots=idle)
# A refresh stamp in the future keeps every call inside the window, so
# the burst runs entirely on speculative counters.
ctl._last_refresh_time = time.perf_counter() + 3600.0
for _ in range(8):
ctl.refresh_load_budget()
ctl.total_tokens_scheduler(_req(input_ids=[0] * 100))
ctl.load_snapshot_reader.read_all.assert_not_called()
self.assertEqual(
ctl.dp_budget.total_tokens,
[200, 200, 200, 200],
"speculative increments should spread the burst evenly",
)
for i, worker in enumerate(ctl.workers):
self.assertEqual(
worker.send_pyobj.call_count, 2, f"worker {i} should get 2 of 8 reqs"
)
def test_refresh_outside_window_overwrites_speculative_increments(self):
reported = [
_load(dp_rank=0, timestamp=2.0, num_total_tokens=10),
_load(dp_rank=1, timestamp=2.0, num_total_tokens=20),
]
ctl = self._controller_with_reader(dp_size=2, snapshots=reported)
ctl._last_refresh_time = 0.0 # window has long passed
ctl.dp_budget.total_tokens = [999, 999]
ctl.refresh_load_budget()
ctl.load_snapshot_reader.read_all.assert_called_once()
self.assertEqual(
ctl.dp_budget.total_tokens,
[10, 20],
"a fresh snapshot must replace the speculative state",
)
self.assertGreater(ctl._last_refresh_time, 0.0)
def test_unchanged_snapshot_does_not_reset_the_burst(self):
frozen = [_load(dp_rank=i, timestamp=1.0, num_total_tokens=0) for i in range(2)]
ctl = self._controller_with_reader(dp_size=2, snapshots=frozen)
ctl._last_refresh_time = 0.0
ctl.refresh_load_budget() # adopts timestamp 1.0
for _ in range(4):
ctl.total_tokens_scheduler(_req(input_ids=[0] * 50))
after_burst = list(ctl.dp_budget.total_tokens)
ctl._last_refresh_time = 0.0 # let the next refresh through the throttle
ctl.refresh_load_budget() # same timestamp -> update_budget skips it
self.assertEqual(
after_burst, [100, 100], "burst should have spread over both ranks"
)
self.assertEqual(
ctl.dp_budget.total_tokens,
after_burst,
"a stale-timestamp snapshot must not wipe the speculative state",
)
if __name__ == "__main__":
unittest.main()