Files
sglang/python/sglang/srt/disaggregation/decode.py
T

1799 lines
74 KiB
Python

"""
Life cycle of a request in the decode server
1. PreallocQueue:
a. Initialize a receiver for each request
b. The request handshakes first, and pre-allocate kv once there is available kv.
c. Move the request to TransferQueue.
2. TransferQueue:
a. Poll the receiver to check the transfer state
b. If the transfer has finished, move the request to waiting queue
3. WaitingQueue:
a. Use the requests in the queue to construct a PrebuiltExtendBatch
b. Skip the prefill forward but only populate metadata
4. RunningBatch:
a. Merge the resolved PrebuiltExtendBatch into running batch to run decoding
"""
from __future__ import annotations
import logging
import time
from collections import deque
from dataclasses import dataclass
from http import HTTPStatus
from typing import TYPE_CHECKING, Dict, List, Optional, Tuple
import numpy as np
import torch
from torch.distributed import ProcessGroup
from sglang.srt.configs.mamba_utils import Mamba2CacheParams
from sglang.srt.constants import GPU_MEMORY_TYPE_KV_CACHE
from sglang.srt.disaggregation.base import KVPoll
from sglang.srt.disaggregation.base.conn import StateType
from sglang.srt.disaggregation.common.conn import CommonKVManager, CommonKVReceiver
from sglang.srt.disaggregation.utils import (
FAKE_BOOTSTRAP_HOST,
DisaggregationMode,
KVClassType,
MetadataBuffers,
ReqToMetadataIdxAllocator,
TransferBackend,
get_kv_class,
is_mla_backend,
poll_and_all_reduce,
poll_and_all_reduce_with_staging,
prepare_abort,
setup_state_kv_args,
)
from sglang.srt.environ import envs
from sglang.srt.layers.dp_attention import get_attention_tp_size
from sglang.srt.managers.schedule_batch import FINISH_ABORT, ScheduleBatch
from sglang.srt.managers.schedule_policy import match_prefix_for_req
from sglang.srt.managers.utils import GenerationBatchResult
from sglang.srt.mem_cache.allocator import BaseTokenToKVPoolAllocator
from sglang.srt.mem_cache.base_prefix_cache import BasePrefixCache, EvictParams
from sglang.srt.mem_cache.common import (
kv_to_page_indices,
page_align_floor,
release_kv_cache,
)
from sglang.srt.mem_cache.deepseek_v4_memory_pool import DeepSeekV4TokenToKVPool
from sglang.srt.mem_cache.memory_pool import (
HybridReqToTokenPool,
KVCache,
ReqToTokenPool,
)
from sglang.srt.mem_cache.swa_memory_pool import SWAKVPool
from sglang.srt.observability.req_time_stats import (
set_schedule_time_batch,
set_time_batch,
)
from sglang.srt.utils import get_num_new_pages
from sglang.srt.utils.network import NetworkAddress
from sglang.srt.utils.torch_memory_saver_adapter import TorchMemorySaverAdapter
logger = logging.getLogger(__name__)
if TYPE_CHECKING:
from sglang.srt.managers.schedule_batch import Req
from sglang.srt.managers.scheduler import Scheduler
from sglang.srt.server_args import ServerArgs
CLIP_MAX_NEW_TOKEN = envs.SGLANG_CLIP_MAX_NEW_TOKENS_ESTIMATION.get()
def _is_fake_transfer(req: Req, server_args: ServerArgs) -> bool:
return req.bootstrap_host == FAKE_BOOTSTRAP_HOST or (
req.bootstrap_host is None
and server_args.disaggregation_transfer_backend == "fake"
)
def _bootstrap_addr(req: Req) -> str:
# FIXME: make a property of a req
return NetworkAddress(req.bootstrap_host, req.bootstrap_port).to_host_port_str()
class DecodeReqToTokenPool:
"""
The difference of DecodeReqToTokenPool and ReqToTokenPool is that
DecodeReqToTokenPool subscribes memory for pre-allocated requests.
In ReqToTokenPool, if `--max-running-requests` is 8,
#pre-allocated + #transfer + #running <= 8, but there are in fact more memory can carry pre-allocated requests.
In DecodeReqToTokenPool, if `--max-running-requests` is 8,
#running <= 8, #pre-allocated + #transfer <= pre_alloc_size, so we can use the free memory to pre-allocate requests to unblock prefill.
"""
def __init__(
self,
size: int,
max_context_len: int,
device: str,
enable_memory_saver: bool,
pre_alloc_size: int,
):
memory_saver_adapter = TorchMemorySaverAdapter.create(
enable=enable_memory_saver
)
self.size = size
# +1 padding row at index 0; see ReqToTokenPool for rationale.
self._alloc_size = size + pre_alloc_size + 1
self.max_context_len = max_context_len
self.device = device
self.pre_alloc_size = pre_alloc_size
with memory_saver_adapter.region(tag=GPU_MEMORY_TYPE_KV_CACHE):
self.req_to_token = torch.zeros(
(self._alloc_size, max_context_len),
dtype=torch.int32,
device=device,
)
self.free_slots = list(range(1, self._alloc_size))
def write(self, indices, values):
self.req_to_token[indices] = values
def available_size(self):
return len(self.free_slots)
def alloc(self, reqs: List["Req"]) -> Optional[List[int]]:
# Indices of reqs that already have a req_pool_idx and will reuse
# their existing slot (e.g. chunked prefill continuing across chunks).
reusing = [i for i, r in enumerate(reqs) if r.req_pool_idx is not None]
assert (
len(reusing) <= 1
), "only one chunked request may reuse req_pool_idx in a batch"
assert all(
reqs[i].inflight_middle_chunks > 0 or reqs[i].kv_committed_len > 0
for i in reusing
), "reusing request must be chunked or have committed KV"
need_size = len(reqs) - len(reusing)
if need_size > len(self.free_slots):
return None
select_index = self.free_slots[:need_size]
self.free_slots = self.free_slots[need_size:]
offset = 0
for r in reqs:
if r.req_pool_idx is None:
r.req_pool_idx = select_index[offset]
offset += 1
return [r.req_pool_idx for r in reqs]
def free(self, req: "Req"):
assert req.req_pool_idx is not None, "request must have req_pool_idx"
self.free_slots.append(req.req_pool_idx)
req.req_pool_idx = None
def clear(self):
self.free_slots = list(range(1, self._alloc_size))
class HybridMambaDecodeReqToTokenPool(HybridReqToTokenPool):
def __init__(
self,
size: int,
max_context_len: int,
device: str,
enable_memory_saver: bool,
cache_params: "Mamba2CacheParams",
mamba_layer_ids: List[int],
speculative_num_draft_tokens: int,
enable_mamba_extra_buffer: bool,
pre_alloc_size: int,
enable_overlap_schedule: bool,
mamba_size: int = None,
start_layer: int = None,
):
DecodeReqToTokenPool.__init__(
self,
size=size,
max_context_len=max_context_len,
device=device,
enable_memory_saver=enable_memory_saver,
pre_alloc_size=pre_alloc_size,
)
self.mamba_ping_pong_track_buffer_size = 2 if enable_overlap_schedule else 1
self.enable_mamba_extra_buffer = enable_mamba_extra_buffer
self.enable_memory_saver = enable_memory_saver
# Each request needs 1 main mamba slot + ping-pong slots when extra_buffer is enabled.
# Cap the pool at max concurrent requests * slots_per_req to avoid allocating failed.
slots_per_req = 1 + (
self.mamba_ping_pong_track_buffer_size if enable_mamba_extra_buffer else 0
)
max_slots_needed = (size + pre_alloc_size) * slots_per_req
if mamba_size is not None:
effective_mamba_size = max(mamba_size, max_slots_needed)
if mamba_size < max_slots_needed:
logger.warning(
"mamba_size (%d) is less than decode side's max_slots_needed (%d = %d reqs * %d slots/req), "
"raising effective_mamba_size to %d",
mamba_size,
max_slots_needed,
size + pre_alloc_size,
slots_per_req,
effective_mamba_size,
)
else:
effective_mamba_size = max_slots_needed
self.start_layer = start_layer if start_layer is not None else 0
self.layer_transfer_counter = None
self._init_mamba_pool(
mamba_size=effective_mamba_size,
mamba_spec_state_size=size + pre_alloc_size,
cache_params=cache_params,
mamba_layer_ids=mamba_layer_ids,
device=device,
enable_mamba_extra_buffer=self.enable_mamba_extra_buffer,
speculative_num_draft_tokens=speculative_num_draft_tokens,
)
def clear(self):
self.free_slots = list(range(1, self._alloc_size))
self.mamba_pool.clear()
@dataclass
class DecodeRequest:
req: Req
kv_receiver: CommonKVReceiver
waiting_for_input: bool = False
metadata_buffer_index: int = -1
@property
def seqlen(self) -> int:
return self.req.seqlen
@property
def priority(self) -> Optional[int]:
return self.req.priority
class DecodePreallocQueue:
"""
Store the requests that are preallocating.
"""
def __init__(
self,
req_to_token_pool: ReqToTokenPool,
token_to_kv_pool_allocator: BaseTokenToKVPoolAllocator,
draft_token_to_kv_pool: Optional[KVCache],
req_to_metadata_buffer_idx_allocator: ReqToMetadataIdxAllocator,
metadata_buffers: MetadataBuffers,
scheduler: Scheduler,
transfer_queue: DecodeTransferQueue,
tree_cache: BasePrefixCache,
gloo_group: ProcessGroup,
tp_rank: int,
tp_size: int,
dp_size: int,
gpu_id: int,
bootstrap_port: int,
max_total_num_tokens: int,
pp_rank: int,
num_reserved_decode_tokens: int,
transfer_backend: TransferBackend,
):
self.req_to_token_pool = req_to_token_pool
self.token_to_kv_pool_allocator = token_to_kv_pool_allocator
self.token_to_kv_pool = token_to_kv_pool_allocator.get_kvcache()
self.draft_token_to_kv_pool = draft_token_to_kv_pool
self.is_mla_backend = is_mla_backend(self.token_to_kv_pool)
self.metadata_buffers = metadata_buffers
self.req_to_metadata_buffer_idx_allocator = req_to_metadata_buffer_idx_allocator
self.scheduler = scheduler
self.transfer_queue = transfer_queue
self.tree_cache = tree_cache
self.gloo_group = gloo_group
self.tp_rank = tp_rank
self.tp_size = tp_size
self.dp_size = dp_size
self.gpu_id = gpu_id
self.bootstrap_port = bootstrap_port
self.max_total_num_tokens = max_total_num_tokens
self.pp_rank = pp_rank
self.num_reserved_decode_tokens = num_reserved_decode_tokens
self.transfer_backend = transfer_backend
# Queue for requests pending pre-allocation
self.queue: List[DecodeRequest] = []
self.retracted_queue: List[Req] = []
self.pending_reqs: List[DecodeRequest] = []
self._ensure_retry_count: Dict[str, int] = {}
self._max_ensure_retries: int = 15 # scheduling cycles
self._ensure_last_attempt_time: Dict[str, float] = {}
self._ensure_retry_interval: float = 1.0 # seconds
self.enable_staging = envs.SGLANG_DISAGG_STAGING_BUFFER.get()
if self.enable_staging and self.is_mla_backend:
raise RuntimeError(
"SGLANG_DISAGG_STAGING_BUFFER is designed for non-MLA models "
"(e.g. GQA, MHA). MLA models should not set this flag."
)
self.kv_manager = self._init_kv_manager()
if self.enable_staging:
self.transfer_queue._init_staging_handler(self.kv_manager)
if (
self.scheduler.tp_worker.is_hybrid_swa
and not self._uses_swa_tail_prealloc()
):
# Fallback for SWA allocators that still allocate the SWA pool at
# full prompt length.
self.max_total_num_tokens = min(
self.max_total_num_tokens,
self.scheduler.tp_worker.model_runner.swa_max_total_num_tokens,
)
def _uses_swa_tail_prealloc(self) -> bool:
return (
isinstance(self.token_to_kv_pool, (SWAKVPool, DeepSeekV4TokenToKVPool))
and self.token_to_kv_pool_allocator.page_size > 1
and hasattr(self.token_to_kv_pool_allocator, "alloc_extend_swa_tail")
)
def _swa_tail_len(self, seq_len: int) -> int:
if not self._uses_swa_tail_prealloc() or seq_len <= 0:
return max(seq_len, 0)
window_size = self.scheduler.sliding_window_size
if window_size is None or window_size <= 0:
return seq_len
page_size = self.token_to_kv_pool_allocator.page_size
window_start = max(0, seq_len - window_size)
window_start = (window_start // page_size) * page_size
return seq_len - window_start
def _swa_retractable_len(self, req: Req) -> int:
if not self._uses_swa_tail_prealloc():
return len(req.origin_input_ids) + len(req.output_ids)
return self._swa_tail_len(len(req.origin_input_ids)) + len(req.output_ids)
def _prealloc_kv_lens(self, req: Req) -> Tuple[int, int]:
allocated_kv_len = len(req.origin_input_ids) + max(len(req.output_ids) - 1, 0)
if self._uses_swa_tail_prealloc():
return allocated_kv_len, self._swa_tail_len(allocated_kv_len)
return allocated_kv_len, allocated_kv_len
def _prealloc_required_tokens(self, req: Req) -> Tuple[int, int]:
full_len, swa_len = self._prealloc_kv_lens(req)
return (
full_len + self.num_reserved_decode_tokens,
swa_len + self.num_reserved_decode_tokens,
)
def _init_kv_manager(self) -> CommonKVManager:
kv_args_class = get_kv_class(self.transfer_backend, KVClassType.KVARGS)
kv_args = kv_args_class()
attn_tp_size = get_attention_tp_size()
kv_args.engine_rank = self.tp_rank % (attn_tp_size)
kv_args.pp_rank = self.pp_rank
kv_args.system_dp_rank = self.scheduler.ps.dp_rank
if self.scheduler.enable_hisparse:
# Direct-to-host: register host pool pointers so P writes to D's host memory
host_pool = self.scheduler.hisparse_coordinator.mem_pool_host
kv_data_ptrs, kv_data_lens, kv_item_lens = (
host_pool.get_contiguous_buf_infos()
)
else:
kv_data_ptrs, kv_data_lens, kv_item_lens = (
self.token_to_kv_pool.get_contiguous_buf_infos()
)
if self.draft_token_to_kv_pool is not None:
# We should also transfer draft model kv cache. The indices are
# always shared with a target model.
draft_kv_data_ptrs, draft_kv_data_lens, draft_kv_item_lens = (
self.draft_token_to_kv_pool.get_contiguous_buf_infos()
)
kv_data_ptrs += draft_kv_data_ptrs
kv_data_lens += draft_kv_data_lens
kv_item_lens += draft_kv_item_lens
kv_args.kv_data_ptrs = kv_data_ptrs
kv_args.kv_data_lens = kv_data_lens
kv_args.kv_item_lens = kv_item_lens
# HiSparse Host pool has page_size=1; use it when hisparse is enabled
kv_args.page_size = (
1 if self.scheduler.enable_hisparse else self.token_to_kv_pool.page_size
)
kv_args.aux_data_ptrs, kv_args.aux_data_lens, kv_args.aux_item_lens = (
self.metadata_buffers.get_buf_infos()
)
setup_state_kv_args(
kv_args,
self.token_to_kv_pool,
self.draft_token_to_kv_pool,
total_kv_layers=self.scheduler.model_config.num_hidden_layers,
req_to_token_pool=getattr(self, "req_to_token_pool", None),
)
kv_args.ib_device = self.scheduler.server_args.disaggregation_ib_device
kv_args.gpu_id = self.scheduler.ps.gpu_id
kv_manager_class = get_kv_class(self.transfer_backend, KVClassType.MANAGER)
kv_manager = kv_manager_class(
kv_args,
DisaggregationMode.DECODE,
self.scheduler.server_args,
self.is_mla_backend,
)
# Staging buffer setup (only when heterogeneous TP staging is enabled)
if self.enable_staging and not self.is_mla_backend:
kv_pool_for_heads = self.token_to_kv_pool
if hasattr(kv_pool_for_heads, "full_kv_pool"):
kv_pool_for_heads = kv_pool_for_heads.full_kv_pool
per_rank_kv_heads = getattr(kv_pool_for_heads, "head_num", 0)
if per_rank_kv_heads > 0:
kv_args.kv_head_num = per_rank_kv_heads
kv_args.total_kv_head_num = per_rank_kv_heads * attn_tp_size
if hasattr(kv_manager, "set_kv_buffer_tensors"):
kv_pool = kv_pool_for_heads
if hasattr(kv_pool, "k_buffer") and hasattr(kv_pool, "v_buffer"):
kv_manager.set_kv_buffer_tensors(
kv_pool.k_buffer, kv_pool.v_buffer, kv_pool.page_size
)
return kv_manager
def add(self, req: Req, is_retracted: bool = False) -> None:
"""Add a request to the pending queue."""
if self._check_if_req_exceed_kv_capacity(req):
return
if is_retracted:
req.retraction_mb_id = None
self.retracted_queue.append(req)
else:
decode_req = self._create_receiver_and_enqueue(req)
# NOTE: fake transfer does not need to resolve prefill dp rank in the pending queue
if _is_fake_transfer(req, self.scheduler.server_args):
decode_req.kv_receiver.init(0)
return
# Fast path: cache-only lookup, no network calls
prefill_dp_rank = self._resolve_prefill_dp_rank(req)
logger.debug(f"prefill_dp_rank: {prefill_dp_rank}")
if prefill_dp_rank is not None:
decode_req.kv_receiver.init(prefill_dp_rank)
return
self.pending_reqs.append(decode_req)
def _match_prefix_and_lock(self, req: Req) -> Tuple[torch.Tensor, int]:
"""
Match a request against the decode-side radix cache, lock the matched
node to prevent eviction, and return the matched prefix information.
"""
result = match_prefix_for_req(
self.tree_cache,
req,
req.origin_input_ids,
cow_mamba=self.tree_cache.supports_mamba(),
include_req=True,
)
prefix_indices = result.device_indices
last_device_node = result.last_device_node
# Always lock to match aggregated scheduling behavior
self.tree_cache.inc_lock_ref(last_device_node)
return prefix_indices, len(prefix_indices)
def _resolve_prefill_dp_rank(self, req: Req) -> Optional[int]:
prefill_info = self.kv_manager.prefill_info_table.get(_bootstrap_addr(req))
# If None, it will go to the slow path and resolve prefill_info by _ensure_prefill_info then cache it
if prefill_info is None:
return None
if req.disagg_prefill_dp_rank is not None:
return req.disagg_prefill_dp_rank
if prefill_info.dp_size == 1:
return 0
if (
prefill_info.follow_bootstrap_room
and not envs.SGLANG_DISAGGREGATION_FORCE_QUERY_PREFILL_DP_RANK.get()
):
return req.bootstrap_room % prefill_info.dp_size
return None
def _create_receiver_and_enqueue(self, req: Req) -> DecodeRequest:
backend = (
TransferBackend.FAKE
if _is_fake_transfer(req, self.scheduler.server_args)
else self.transfer_backend
)
kv_receiver_class = get_kv_class(backend, KVClassType.RECEIVER)
kv_receiver = kv_receiver_class(
mgr=self.kv_manager,
bootstrap_addr=_bootstrap_addr(req),
bootstrap_room=req.bootstrap_room,
)
decode_req = DecodeRequest(req=req, kv_receiver=kv_receiver)
self.queue.append(decode_req)
return decode_req
def _check_if_req_exceed_kv_capacity(self, req: Req) -> bool:
if len(req.origin_input_ids) > self.max_total_num_tokens:
message = f"Request {req.rid} exceeds the maximum number of tokens: {len(req.origin_input_ids)} > {self.max_total_num_tokens}"
logger.error(message)
prepare_abort(req, message, status_code=HTTPStatus.BAD_REQUEST)
self.scheduler.output_streamer.stream_output([req], req.return_logprob)
return True
if self._uses_swa_tail_prealloc():
_, swa_required = self._prealloc_required_tokens(req)
swa_capacity = self.token_to_kv_pool_allocator.size_swa
if swa_required > swa_capacity:
message = (
f"Request {req.rid} requires too many SWA KV tokens for "
f"decode preallocation: {swa_required} > {swa_capacity}"
)
logger.error(message)
prepare_abort(req, message, status_code=HTTPStatus.BAD_REQUEST)
self.scheduler.output_streamer.stream_output([req], req.return_logprob)
return True
return False
def extend(self, reqs: List[Req], is_retracted: bool = False) -> None:
"""Add a request to the pending queue."""
for req in reqs:
self.add(req, is_retracted=is_retracted)
def resume_retracted_reqs(
self, rids_to_check: Optional[List[str]] = None
) -> List[Req]:
# TODO refactor the scheduling part, reuse with the unified engine logic as much as possible
# allocate memory
resumed_reqs = []
indices_to_remove = set()
uses_swa_tail_prealloc = self._uses_swa_tail_prealloc()
if uses_swa_tail_prealloc:
full_allocatable_tokens, swa_allocatable_tokens = (
self._swa_aware_allocatable_token_budgets(count_retracted=False)
)
else:
full_allocatable_tokens = self._allocatable_token_budgets(
count_retracted=False
)
for i, req in enumerate(self.retracted_queue):
if rids_to_check is not None and req.rid not in rids_to_check:
continue
if self.req_to_token_pool.available_size() <= 0:
break
full_required, swa_required = self._prealloc_required_tokens(req)
if full_required > full_allocatable_tokens:
break
if uses_swa_tail_prealloc and swa_required > swa_allocatable_tokens:
break
resumed_reqs.append(req)
indices_to_remove.add(i)
req.is_retracted = False
self._pre_alloc(req)
full_allocatable_tokens -= full_required
if uses_swa_tail_prealloc:
swa_allocatable_tokens -= swa_required
# load from cpu, release the cpu copy
req.load_kv_cache(self.req_to_token_pool, self.token_to_kv_pool_allocator)
self.retracted_queue = [
entry
for i, entry in enumerate(self.retracted_queue)
if i not in indices_to_remove
]
return resumed_reqs
def _update_handshake_waiters(
self, rids_to_check: Optional[List[str]] = None
) -> None:
if not self.queue:
return
# Still poll if any receiver was aborted, otherwise it stays stuck.
if all(decode_req.waiting_for_input for decode_req in self.queue) and not any(
getattr(decode_req.kv_receiver, "conclude_state", None) == KVPoll.Failed
for decode_req in self.queue
):
return
polls = poll_and_all_reduce(
[decode_req.kv_receiver for decode_req in self.queue], self.gloo_group
)
for i, (decode_req, poll) in enumerate(zip(self.queue, polls)):
if rids_to_check is not None and decode_req.req.rid not in rids_to_check:
continue
if poll == KVPoll.Bootstrapping:
pass
elif poll == KVPoll.WaitingForInput:
decode_req.waiting_for_input = True
decode_req.req.time_stats.set_bootstrap_done_time()
elif poll == KVPoll.Failed:
error_message = f"Decode handshake failed for request rank={self.tp_rank} {decode_req.req.rid=} {decode_req.req.bootstrap_room=}"
try:
decode_req.kv_receiver.failure_exception()
except Exception as e:
error_message += f" with exception {e}"
logger.error(error_message)
prepare_abort(
decode_req.req,
error_message,
status_code=HTTPStatus.INTERNAL_SERVER_ERROR,
)
if self.scheduler.metrics_reporter.enable_metrics:
self.scheduler.metrics_collector.increment_bootstrap_failed_reqs()
else:
raise ValueError(f"Unexpected poll case: {poll}")
def _ensure_prefill_info(
self, addr_to_reqs: Dict[str, List[DecodeRequest]]
) -> Tuple[Dict[str, List[DecodeRequest]], List[DecodeRequest]]:
"""Non-blocking ensure parallel info for each addr.
Returns (ready_addrs, remaining_reqs)."""
ready: Dict[str, List[DecodeRequest]] = {}
remaining: List[DecodeRequest] = []
now = time.monotonic()
for bootstrap_addr, reqs in addr_to_reqs.items():
last_attempt = self._ensure_last_attempt_time.get(bootstrap_addr)
if last_attempt is not None and (
now - last_attempt < self._ensure_retry_interval
):
remaining.extend(reqs)
continue
self._ensure_last_attempt_time[bootstrap_addr] = now
if self.kv_manager.try_ensure_parallel_info(bootstrap_addr):
if bootstrap_addr in self._ensure_retry_count:
del self._ensure_retry_count[bootstrap_addr]
if bootstrap_addr in self._ensure_last_attempt_time:
del self._ensure_last_attempt_time[bootstrap_addr]
ready[bootstrap_addr] = reqs
continue
count = self._ensure_retry_count.get(bootstrap_addr, 0) + 1
self._ensure_retry_count[bootstrap_addr] = count
if count >= self._max_ensure_retries:
error_msg = f"Could not fetch prefill parallel info from {bootstrap_addr} after {count} attempts"
logger.error(error_msg)
for decode_req in reqs:
decode_req.kv_receiver.abort()
del self._ensure_retry_count[bootstrap_addr]
del self._ensure_last_attempt_time[bootstrap_addr]
else:
remaining.extend(reqs)
return ready, remaining
def _resolve_pending_reqs(self) -> None:
"""Batch-resolve prefill_dp_ranks for pending requests and initialize receivers."""
if not self.pending_reqs:
return
# Group pending requests by bootstrap_addr
addr_to_reqs: Dict[str, List[DecodeRequest]] = {}
for decode_req in self.pending_reqs:
addr = _bootstrap_addr(decode_req.req)
addr_to_reqs.setdefault(addr, []).append(decode_req)
# Pass 1: ensure parallel info for each addr
ready_addrs, remaining = self._ensure_prefill_info(addr_to_reqs)
resolved: List[Tuple[DecodeRequest, int]] = []
for bootstrap_addr, decode_reqs in ready_addrs.items():
need_query: List[DecodeRequest] = []
for decode_req in decode_reqs:
prefill_dp_rank = self._resolve_prefill_dp_rank(decode_req.req)
if prefill_dp_rank is not None:
resolved.append((decode_req, prefill_dp_rank))
else:
need_query.append(decode_req)
# Pass 2: resolve dp rank for addrs whose info is available
if need_query:
rooms = [decode_req.req.bootstrap_room for decode_req in need_query]
room_to_rank = CommonKVReceiver.query_prefill_dp_ranks(
bootstrap_addr, rooms
)
for decode_req in need_query:
prefill_dp_rank = room_to_rank.get(
str(decode_req.req.bootstrap_room)
)
if prefill_dp_rank is not None:
resolved.append((decode_req, int(prefill_dp_rank)))
else:
remaining.append(decode_req)
self.pending_reqs = remaining
for decode_req, prefill_dp_rank in resolved:
decode_req.kv_receiver.init(prefill_dp_rank)
def pop_preallocated(
self, rids_to_check: Optional[List[str]] = None
) -> Tuple[List[DecodeRequest], List[DecodeRequest]]:
"""Pop the preallocated requests from the pending queue (FIFO)."""
self._resolve_pending_reqs()
self._update_handshake_waiters(rids_to_check)
failed_reqs = []
preallocated_reqs = []
indices_to_remove = set()
# We need to make sure that the sum of inflight tokens and allocatable tokens is greater than maximum input+output length of each inflight request
# Otherwise it is possible for one request running decode out of memory, while all other requests are in the transfer queue that cannot be retracted.
retractable_tokens = sum(
len(r.origin_input_ids) + len(r.output_ids)
for r in self.scheduler.running_batch.reqs
)
uses_swa_tail_prealloc = self._uses_swa_tail_prealloc()
swa_allocatable_tokens = 0
if uses_swa_tail_prealloc:
retractable_swa_tokens = sum(
self._swa_retractable_len(r) for r in self.scheduler.running_batch.reqs
)
full_allocatable_tokens, swa_allocatable_tokens = (
self._swa_aware_allocatable_token_budgets(
retractable_tokens=retractable_tokens,
retractable_swa_tokens=retractable_swa_tokens,
count_retracted=True,
)
)
else:
retractable_swa_tokens = 0
full_allocatable_tokens = self._allocatable_token_budgets(
retractable_tokens=retractable_tokens, count_retracted=True
)
# Sort by priority before any index-based bookkeeping so that both the
# abort-scan loop and the preallocation loop operate on the same order.
if self.scheduler.enable_priority_scheduling:
priority_sign = (
1 if self.scheduler.schedule_low_priority_values_first else -1
)
self.queue.sort(key=lambda r: r.req.priority * priority_sign)
# First, remove all failed requests from the queue
for i, decode_req in enumerate(self.queue):
if rids_to_check is not None and decode_req.req.rid not in rids_to_check:
continue
if isinstance(decode_req.req.finished_reason, FINISH_ABORT):
self.scheduler.output_streamer.stream_output(
[decode_req.req],
decode_req.req.return_logprob,
)
failed_reqs.append(decode_req)
indices_to_remove.add(i)
# HiSparse physical constraint: max requests by device buffer capacity.
# Each admitted req needs padded_buffer_size from hisparse device pool.
# waiting_queue reqs already have device buffers (allocated in admit_request_direct),
# only transfer_queue reqs are pending device buffer allocation.
hisparse_req_budget = float("inf")
if self.scheduler.enable_hisparse:
hisparse_avail = (
self.token_to_kv_pool_allocator.hisparse_attn_allocator.available_size()
)
hisparse_req_budget = max(
0,
hisparse_avail // self.scheduler.hisparse_coordinator.padded_buffer_size
- len(self.transfer_queue.queue),
)
# Then, preallocate the remaining requests if possible
for i, decode_req in enumerate(self.queue):
if rids_to_check is not None and decode_req.req.rid not in rids_to_check:
continue
if i in indices_to_remove:
continue
if not decode_req.waiting_for_input:
continue
if self.req_to_token_pool.available_size() <= 0:
break
if self.req_to_metadata_buffer_idx_allocator.available_size() <= 0:
break
if hisparse_req_budget <= 0:
break
# Memory estimation: don't add if the projected memory cannot be met
# TODO: add new_token ratio
origin_input_len = len(decode_req.req.origin_input_ids)
if self.scheduler.server_args.disaggregation_decode_enable_radix_cache:
# Match prefix against decode's radix cache.
prefix_indices, prefix_len = self._match_prefix_and_lock(decode_req.req)
# Align prefix_len down to page boundary so both prefill and
# decode agree on the page-aligned split point for KV transfer.
page_size = self.token_to_kv_pool_allocator.page_size
if page_size > 1 and prefix_len % page_size != 0:
prefix_len = page_align_floor(prefix_len, page_size)
prefix_indices = prefix_indices[:prefix_len]
fill_len = origin_input_len + max(len(decode_req.req.output_ids) - 1, 0)
required_alloc_tokens = self._required_alloc_tokens(
fill_len=fill_len, prefix_len=prefix_len
)
# Matching may lock previously-evictable radix pages, so refresh
# the admission budget against the post-lock pool state before we
# decide whether this request still fits.
full_allocatable_tokens = self._allocatable_token_budgets(
retractable_tokens=retractable_tokens,
count_retracted=True,
extra_reserved_reqs=len(preallocated_reqs),
)
else:
prefix_indices = None
prefix_len = 0
required_alloc_tokens = origin_input_len
required_tokens_for_request = (
required_alloc_tokens + self.num_reserved_decode_tokens
)
if (
max(
required_tokens_for_request,
origin_input_len
- prefix_len
+ min(
decode_req.req.sampling_params.max_new_tokens,
CLIP_MAX_NEW_TOKEN,
)
- retractable_tokens,
)
> full_allocatable_tokens
):
if prefix_len > 0:
self.tree_cache.dec_lock_ref(decode_req.req.last_node)
break
if required_tokens_for_request > full_allocatable_tokens:
if prefix_len > 0:
self.tree_cache.dec_lock_ref(decode_req.req.last_node)
break
if uses_swa_tail_prealloc:
_, swa_required = self._prealloc_required_tokens(decode_req.req)
_, swa_len = self._prealloc_kv_lens(decode_req.req)
max_new_tokens = min(
decode_req.req.sampling_params.max_new_tokens,
CLIP_MAX_NEW_TOKEN,
)
if (
max(
swa_required,
swa_len + max_new_tokens - retractable_swa_tokens,
)
> swa_allocatable_tokens
):
if prefix_len > 0:
self.tree_cache.dec_lock_ref(decode_req.req.last_node)
break
dst_kv_indices = self._pre_alloc(decode_req.req, prefix_indices, prefix_len)
hisparse_req_budget -= 1
# Recompute from actual pool state for the next queue entry.
# This accounts for page rounding and newly locked evictable cache.
full_allocatable_tokens = self._allocatable_token_budgets(
retractable_tokens=retractable_tokens,
count_retracted=True,
extra_reserved_reqs=len(preallocated_reqs) + 1,
)
if uses_swa_tail_prealloc:
# SWA budget uses simple decrement (no radix cache eviction in
# the SWA pool, so page-rounding drift is negligible).
swa_allocatable_tokens -= swa_required
decode_req.req.cache_protected_len = prefix_len
if self.scheduler.enable_hisparse:
# Must cast to int32 for ZMQ serialization -- from_zmq reads np.int32.
kv_indices = (
dst_kv_indices[: origin_input_len - prefix_len]
.cpu()
.numpy()
.astype(np.int32)
)
page_size = 1 # host pool page_size
else:
# Only send delta indices (beyond prefix) to prefill.
kv_indices = (
self.req_to_token_pool.req_to_token[decode_req.req.req_pool_idx][
prefix_len:origin_input_len
]
.cpu()
.numpy()
)
page_size = self.token_to_kv_pool_allocator.page_size
seq_len = len(decode_req.req.origin_input_ids)
def _mamba_payload():
return [
self.req_to_token_pool.req_index_to_mamba_index_mapping[
decode_req.req.req_pool_idx
]
.cpu()
.numpy()
]
def _swa_payload():
window_size = self.scheduler.sliding_window_size
window_start = max(0, seq_len - window_size)
window_start = page_align_floor(window_start, page_size)
window_kv_indices_full = self.req_to_token_pool.req_to_token[
decode_req.req.req_pool_idx, window_start:seq_len
]
window_kv_indices_swa = (
self.token_to_kv_pool_allocator.translate_loc_from_full_to_swa(
window_kv_indices_full
)
)
return kv_to_page_indices(
window_kv_indices_swa.cpu().numpy(), page_size
)
def _nsa_payload():
kv_indices_full = self.req_to_token_pool.req_to_token[
decode_req.req.req_pool_idx, :seq_len
]
# Indexer lives on device pool; always use device page_size
device_page_size = self.token_to_kv_pool.page_size
return kv_to_page_indices(
kv_indices_full.cpu().numpy(), device_page_size
)
state_types = self.kv_manager.kv_args.state_types
state_indices: Optional[List] = []
for st in state_types:
if st == StateType.MAMBA:
state_indices.append(_mamba_payload())
elif st == StateType.SWA:
state_indices.append(_swa_payload())
elif st == StateType.NSA:
state_indices.append(_nsa_payload())
else:
state_indices.append(None)
decode_req.metadata_buffer_index = (
self.req_to_metadata_buffer_idx_allocator.alloc()
)
assert decode_req.metadata_buffer_index is not None
page_indices = kv_to_page_indices(kv_indices, page_size)
decode_req.kv_receiver.send_metadata(
page_indices,
decode_req.metadata_buffer_index,
state_indices,
decode_prefix_len=prefix_len,
)
if (
self.transfer_queue.enable_staging
and hasattr(decode_req.kv_receiver, "require_staging")
and decode_req.kv_receiver.require_staging
):
self.transfer_queue.staging_handler.register_decode_req(
decode_req.req.bootstrap_room, decode_req
)
preallocated_reqs.append(decode_req)
indices_to_remove.add(i)
decode_req.req.time_stats.set_decode_transfer_queue_entry_time()
self.queue = [
entry for i, entry in enumerate(self.queue) if i not in indices_to_remove
]
return preallocated_reqs, failed_reqs
@property
def num_tokens_pre_allocated(self):
return sum(
len(decode_req.req.fill_ids) for decode_req in self.transfer_queue.queue
)
def _need_space_for_single_req(
self, retractable_tokens: Optional[int] = None
) -> int:
need_space_for_single_req = (
max(
[
min(x.sampling_params.max_new_tokens, CLIP_MAX_NEW_TOKEN)
+ len(x.origin_input_ids)
- retractable_tokens
for x in self.scheduler.running_batch.reqs
]
)
if retractable_tokens is not None
and len(self.scheduler.running_batch.reqs) > 0
else 0
)
return need_space_for_single_req
def _active_req_count(self, extra_reserved_reqs: int = 0) -> int:
return (
len(self.scheduler.running_batch.reqs)
+ len(self.transfer_queue.queue)
+ len(self.scheduler.waiting_queue)
+ extra_reserved_reqs
)
def _active_reserved_tokens(
self, n_active: Optional[int] = None, extra_reserved_reqs: int = 0
) -> int:
if n_active is None:
n_active = self._active_req_count(extra_reserved_reqs)
return self.num_reserved_decode_tokens * n_active
def _swa_aware_allocatable_token_budgets(
self,
retractable_tokens: Optional[int] = None,
retractable_swa_tokens: Optional[int] = None,
count_retracted: bool = True,
) -> Tuple[int, int]:
n_active = self._active_req_count()
reserved_tokens = self._active_reserved_tokens(n_active)
full_allocatable_tokens = self._allocatable_token_budgets(
retractable_tokens=retractable_tokens,
count_retracted=count_retracted,
reserved_tokens=reserved_tokens,
)
return full_allocatable_tokens, self._swa_tail_allocatable_token_budget(
retractable_tokens=retractable_tokens,
retractable_swa_tokens=retractable_swa_tokens,
count_retracted=count_retracted,
n_active=n_active,
reserved_tokens=reserved_tokens,
)
def _allocatable_token_budgets(
self,
retractable_tokens: Optional[int] = None,
count_retracted: bool = True,
extra_reserved_reqs: int = 0,
reserved_tokens: Optional[int] = None,
) -> int:
need_space_for_single_req = self._need_space_for_single_req(retractable_tokens)
if reserved_tokens is None:
reserved_tokens = self._active_reserved_tokens(
extra_reserved_reqs=extra_reserved_reqs
)
if self.scheduler.enable_hisparse:
# HiSparse pre-alloc only allocates logical indices (alloc_logical_only),
# so the logical pool is the binding constraint for admission control.
available_size = (
self.token_to_kv_pool_allocator.logical_attn_allocator.available_size()
)
elif self._uses_swa_tail_prealloc():
available_size = self.token_to_kv_pool_allocator.full_available_size()
if self.scheduler.server_args.disaggregation_decode_enable_radix_cache:
available_size += self.tree_cache.evictable_size()
else:
available_size = self.token_to_kv_pool_allocator.available_size()
# Include evictable decode-radix cache entries in the budget -- they
# can be freed on demand before allocation.
if self.scheduler.server_args.disaggregation_decode_enable_radix_cache:
available_size += self.tree_cache.evictable_size()
allocatable_tokens = available_size - max(
reserved_tokens, need_space_for_single_req
)
# Note: if the last prebuilt extend just finishes, and we enter `pop_preallocated` immediately in the next iteration
# the extend batch is not in any queue, so we need to explicitly add the tokens slots here
if (
self.scheduler.last_batch
and self.scheduler.last_batch.forward_mode.is_prebuilt()
):
allocatable_tokens -= self.num_reserved_decode_tokens * len(
self.scheduler.last_batch.reqs
)
if count_retracted:
for req in self.retracted_queue:
full_required, _ = self._prealloc_required_tokens(req)
allocatable_tokens -= full_required
return allocatable_tokens
def _swa_tail_allocatable_token_budget(
self,
retractable_tokens: Optional[int] = None,
retractable_swa_tokens: Optional[int] = None,
count_retracted: bool = True,
n_active: Optional[int] = None,
reserved_tokens: Optional[int] = None,
) -> int:
need_swa_space_for_single_req = self._need_space_for_single_req(
retractable_tokens
)
if (
retractable_swa_tokens is not None
and len(self.scheduler.running_batch.reqs) > 0
):
need_swa_space_for_single_req = max(
self._swa_tail_len(len(x.origin_input_ids))
+ min(x.sampling_params.max_new_tokens, CLIP_MAX_NEW_TOKEN)
- retractable_swa_tokens
for x in self.scheduler.running_batch.reqs
)
if n_active is None:
n_active = self._active_req_count()
if reserved_tokens is None:
reserved_tokens = self._active_reserved_tokens(n_active)
# SWA growth is bounded by the sliding window: once a req's SWA
# footprint reaches `sliding_window_size`, further decode tokens
# evict old ones and net growth is zero. The linear reservation
# `num_reserved_decode_tokens * n_active` (correct for the full
# pool) over-reserves SWA in steady state. Cap by the actual
# remaining headroom up to per-req window cap.
window_size = self.scheduler.sliding_window_size or 0
swa_total = self.token_to_kv_pool_allocator.size_swa
swa_used = swa_total - self.token_to_kv_pool_allocator.swa_available_size()
swa_growth_potential = max(0, n_active * window_size - swa_used)
swa_reserved_tokens = min(reserved_tokens, swa_growth_potential)
swa_allocatable_tokens = (
self.token_to_kv_pool_allocator.swa_available_size()
- max(swa_reserved_tokens, need_swa_space_for_single_req)
)
# Note: if the last prebuilt extend just finishes, and we enter `pop_preallocated` immediately in the next iteration
# the extend batch is not in any queue, so we need to explicitly add the tokens slots here
if (
self.scheduler.last_batch
and self.scheduler.last_batch.forward_mode.is_prebuilt()
):
prebuilt_reserved_tokens = self.num_reserved_decode_tokens * len(
self.scheduler.last_batch.reqs
)
prebuilt_n = len(self.scheduler.last_batch.reqs)
prebuilt_swa_growth = max(0, prebuilt_n * window_size - swa_used)
swa_allocatable_tokens -= min(prebuilt_reserved_tokens, prebuilt_swa_growth)
if count_retracted:
for req in self.retracted_queue:
_, swa_required = self._prealloc_required_tokens(req)
swa_allocatable_tokens -= swa_required
return swa_allocatable_tokens
def _required_alloc_tokens(self, *, fill_len: int, prefix_len: int) -> int:
page_size = self.token_to_kv_pool_allocator.page_size
if page_size == 1:
return fill_len - prefix_len
num_new_pages = get_num_new_pages(
seq_lens=torch.tensor([fill_len], dtype=torch.int64),
prefix_lens=torch.tensor([prefix_len], dtype=torch.int64),
page_size=page_size,
)
return num_new_pages * page_size
def _pre_alloc(
self,
req: Req,
prefix_indices: Optional[torch.Tensor] = None,
prefix_len: Optional[int] = None,
) -> torch.Tensor:
"""Pre-allocate the memory for req_to_token and token_kv_pool"""
if prefix_len is None:
prefix_len = 0
req_pool_indices = self.req_to_token_pool.alloc([req])
assert (
req_pool_indices is not None
), "req_pool_indices is full! There is a bug in memory estimation."
fill_len = len(req.origin_input_ids) + max(len(req.output_ids) - 1, 0)
req.kv_allocated_len = fill_len
req.kv_committed_len = fill_len
if prefix_len > 0:
self.req_to_token_pool.write(
(req.req_pool_idx, slice(0, prefix_len)), prefix_indices
)
# TODO(retraction): when retraction is implemented with radix cache
# awareness, a retracted request should re-match the tree here
# instead of re-allocating from scratch. See resume_retracted_reqs.
delta_len = fill_len - prefix_len
required_alloc_tokens = self._required_alloc_tokens(
fill_len=fill_len, prefix_len=prefix_len
)
# Evict cached entries if the pool doesn't have enough free pages.
if (
self.scheduler.server_args.disaggregation_decode_enable_radix_cache
and self.token_to_kv_pool_allocator.available_size() < required_alloc_tokens
):
num_to_evict = (
required_alloc_tokens - self.token_to_kv_pool_allocator.available_size()
)
result = self.tree_cache.evict(EvictParams(num_tokens=num_to_evict))
if self.token_to_kv_pool_allocator.available_size() < required_alloc_tokens:
logger.warning(
f"Eviction insufficient: needed {required_alloc_tokens} tokens, "
f"available {self.token_to_kv_pool_allocator.available_size()} "
f"after evicting {result.num_tokens_evicted}/{num_to_evict} tokens. "
f"evictable_size={self.tree_cache.evictable_size()}, "
f"protected_size={self.tree_cache.protected_size()}, "
f"fill_len={fill_len}, prefix_len={prefix_len}, delta_len={delta_len}, "
f"page_size={self.token_to_kv_pool_allocator.page_size}, "
f"req={req.rid}"
)
if self.scheduler.enable_hisparse:
# HiSparse is incompatible with decode-side L1 radix cache. Keep
# this path on the upstream full-allocation semantics.
assert prefix_len == 0
# Direct-to-host path: only allocate logical indices (no hisparse
# device indices) and allocate host indices for RDMA destination.
coordinator = self.scheduler.hisparse_coordinator
device = self.token_to_kv_pool_allocator.device
kv_loc = self.token_to_kv_pool_allocator.alloc_logical_only(
prefix_lens=torch.tensor([0], dtype=torch.int64, device=device),
prefix_lens_cpu=torch.tensor([0], dtype=torch.int64),
seq_lens=torch.tensor([fill_len], dtype=torch.int64, device=device),
seq_lens_cpu=torch.tensor([fill_len], dtype=torch.int64),
last_loc=torch.tensor([-1], dtype=torch.int64, device=device),
extend_num_tokens=fill_len,
)
# Allocate host indices for the RDMA transfer target.
host_indices = coordinator.mem_pool_host.alloc(fill_len)
if host_indices is None:
raise RuntimeError(
f"HiSparse host mem pool alloc failed for {fill_len} tokens "
f"in _pre_alloc (req {req.rid})"
)
host_indices = host_indices.to(device=coordinator.device)
coordinator.req_to_host_pool[req.req_pool_idx, :fill_len] = host_indices
elif self.token_to_kv_pool_allocator.page_size == 1:
kv_loc = self.token_to_kv_pool_allocator.alloc(delta_len)
else:
device = self.token_to_kv_pool_allocator.device
last_loc = (
prefix_indices[-1:].to(dtype=torch.int64, device=device)
if prefix_len > 0
else torch.tensor([-1], dtype=torch.int64, device=device)
)
if self._uses_swa_tail_prealloc() and prefix_len == 0:
# Tail-only SWA allocation: only valid when prefix_len == 0.
# When prefix_len > 0 (radix cache hit), we fall back to
# alloc_extend which allocates SWA at full page count; the
# SWA budget in that case may slightly under-estimate.
kv_loc = self.token_to_kv_pool_allocator.alloc_extend_swa_tail(
prefix_lens=torch.tensor([0], dtype=torch.int64, device=device),
prefix_lens_cpu=torch.tensor([0], dtype=torch.int64),
seq_lens=torch.tensor([fill_len], dtype=torch.int64, device=device),
seq_lens_cpu=torch.tensor([fill_len], dtype=torch.int64),
last_loc=last_loc,
extend_num_tokens=fill_len,
swa_tail_len=self._swa_tail_len(fill_len),
)
else:
kv_loc = self.token_to_kv_pool_allocator.alloc_extend(
prefix_lens=torch.tensor(
[prefix_len], dtype=torch.int64, device=device
),
prefix_lens_cpu=torch.tensor([prefix_len], dtype=torch.int64),
seq_lens=torch.tensor([fill_len], dtype=torch.int64, device=device),
seq_lens_cpu=torch.tensor([fill_len], dtype=torch.int64),
last_loc=last_loc,
extend_num_tokens=delta_len,
)
assert kv_loc is not None, (
f"KV cache is full! Bug in memory estimation. "
f"available={self.token_to_kv_pool_allocator.available_size()}, "
f"evictable={self.tree_cache.evictable_size()}, "
f"protected={self.tree_cache.protected_size()}, "
f"required_alloc={required_alloc_tokens}, delta={delta_len}, "
f"fill={fill_len}, prefix={prefix_len}, "
f"page_size={self.token_to_kv_pool_allocator.page_size}, "
f"req={req.rid}"
)
self.req_to_token_pool.write(
(req.req_pool_idx, slice(prefix_len, prefix_len + len(kv_loc))), kv_loc
)
# Truncate fill_ids to kv_committed_len so cache_unfinished_req only
# inserts committed KV into the radix tree. The last output token
# hasn't had KV committed yet (fill_ids is 1 ahead).
req.fill_ids = (req.origin_input_ids + req.output_ids)[: req.kv_committed_len]
# Set prefix_indices so downstream consumers (init_next_round_input,
# prepare_for_extend) see the correct prefix length. In the agg path
# this is done inside init_next_round_input, but decode-disagg needs
# allocation info before batch assembly so we set it here.
req.prefix_indices = (
prefix_indices if prefix_len > 0 else torch.empty((0,), dtype=torch.int64)
)
req.set_extend_input_len(len(req.fill_ids) - prefix_len)
# Return the transfer destination indices:
if self.scheduler.enable_hisparse:
return host_indices
return kv_loc
class DecodeTransferQueue:
"""
Store the requests that is polling kv
"""
def __init__(
self,
gloo_group: ProcessGroup,
req_to_metadata_buffer_idx_allocator: ReqToMetadataIdxAllocator,
tp_rank: int,
metadata_buffers: MetadataBuffers,
scheduler: Scheduler,
tree_cache: BasePrefixCache,
):
self.queue: List[DecodeRequest] = []
self.gloo_group = gloo_group
self.req_to_metadata_buffer_idx_allocator = req_to_metadata_buffer_idx_allocator
self.tp_rank = tp_rank
self.metadata_buffers = metadata_buffers
self.scheduler = scheduler
self.tree_cache = tree_cache
self.spec_algorithm = scheduler.spec_algorithm
self.enable_staging = envs.SGLANG_DISAGG_STAGING_BUFFER.get()
self.staging_handler = None
def add(self, decode_req: DecodeRequest) -> None:
self.queue.append(decode_req)
def extend(self, decode_reqs: List[DecodeRequest]) -> None:
self.queue.extend(decode_reqs)
if self.enable_staging:
for dr in decode_reqs:
if (
hasattr(dr.kv_receiver, "require_staging")
and dr.kv_receiver.require_staging
):
self.staging_handler.register_decode_req(dr.req.bootstrap_room, dr)
def _commit_transfer_to_req(self, decode_req: DecodeRequest) -> bool:
"""
Returns:
True if the request should be removed from the queue (success or corruption)
False if metadata not ready yet (keep in queue for next poll)
"""
idx = decode_req.metadata_buffer_index
(
output_id,
cached_tokens,
output_token_logprobs_val,
output_token_logprobs_idx,
output_top_logprobs_val,
output_top_logprobs_idx,
output_topk_p,
output_topk_index,
output_hidden_states,
output_bootstrap_room,
) = self.metadata_buffers.get_buf(idx)
# Validate bootstrap_room to detect context corruption
actual_room = output_bootstrap_room[0].item()
expected_room = (
decode_req.req.bootstrap_room
if decode_req.req.bootstrap_room is not None
else 0
)
if _is_fake_transfer(decode_req.req, self.scheduler.server_args):
pass
elif actual_room == 0:
# Case 1: Metadata not ready yet (actual_room == 0)
# Keep request in queue and wait for next poll
return False
elif actual_room != expected_room:
# Case 2: Real corruption detected (mismatch)
# Abort the request and remove from the queue
error_msg = (
f"Context corruption detected: Request {decode_req.req.rid} "
f"(bootstrap_room={expected_room}) received metadata from "
f"bootstrap_room={actual_room}. "
f"Metadata buffer index: {idx}. "
f"This indicates metadata buffer index collision."
)
logger.error(error_msg)
prepare_abort(
decode_req.req,
"Metadata corruption detected - bootstrap_room mismatch",
status_code=HTTPStatus.INTERNAL_SERVER_ERROR,
)
decode_req.kv_receiver.clear()
decode_req.kv_receiver = None
return True
# Case 3: Success - commit the transfer
decode_req.req.output_ids.append(output_id[0].item())
decode_req.req.cached_tokens = cached_tokens[0].item()
decode_req.req.cached_tokens_device = cached_tokens[1].item()
decode_req.req.cached_tokens_host = cached_tokens[2].item()
decode_req.req.cached_tokens_storage = cached_tokens[3].item()
if not self.spec_algorithm.is_none():
decode_req.req.output_topk_p = output_topk_p
decode_req.req.output_topk_index = output_topk_index
decode_req.req.hidden_states_tensor = output_hidden_states
if decode_req.req.return_logprob:
decode_req.req.logprob.output_token_logprobs_val.append(
output_token_logprobs_val[0].item()
)
decode_req.req.logprob.output_token_logprobs_idx.append(
output_token_logprobs_idx[0].item()
)
decode_req.req.logprob.output_top_logprobs_val.append(
output_top_logprobs_val[
: decode_req.req.logprob.top_logprobs_num
].tolist()
)
decode_req.req.logprob.output_top_logprobs_idx.append(
output_top_logprobs_idx[
: decode_req.req.logprob.top_logprobs_num
].tolist()
)
decode_req.kv_receiver.clear()
decode_req.kv_receiver = None
decode_req.req.time_stats.set_wait_queue_entry_time()
return True
def _poll_with_staging(self) -> list:
return poll_and_all_reduce_with_staging(
self.queue, self.staging_handler, self.gloo_group
)
def _init_staging_handler(self, kv_manager):
"""Create staging handler from kv_manager. Must be called exactly once."""
from sglang.srt.disaggregation.common.staging_handler import (
DecodeStagingHandler,
)
self.staging_handler = DecodeStagingHandler.create(
kv_manager, self.scheduler, self.tp_rank
)
kv_manager._staging_handler = self.staging_handler
def pop_transferred(self, rids_to_check: Optional[List[str]] = None) -> List[Req]:
if not self.queue:
return []
if self.enable_staging:
polls = self._poll_with_staging()
else:
polls = poll_and_all_reduce(
[dr.kv_receiver for dr in self.queue], self.gloo_group
)
transferred_reqs = []
indices_to_remove = set()
for i, (decode_req, poll) in enumerate(zip(self.queue, polls)):
if rids_to_check is not None and decode_req.req.rid not in rids_to_check:
continue
if poll == KVPoll.Failed:
error_message = f"Decode transfer failed for request rank={self.tp_rank} {decode_req.req.rid=} {decode_req.req.bootstrap_room=}"
try:
decode_req.kv_receiver.failure_exception()
except Exception as e:
error_message += f" with exception {e}"
logger.error(error_message)
prepare_abort(
decode_req.req,
error_message,
status_code=HTTPStatus.INTERNAL_SERVER_ERROR,
)
self.scheduler.output_streamer.stream_output(
[decode_req.req],
decode_req.req.return_logprob,
)
if self.scheduler.enable_hisparse:
self.scheduler.hisparse_coordinator.request_finished(decode_req.req)
# release pre-allocated kv cache, but don't insert into the tree since it's failed
release_kv_cache(decode_req.req, self.tree_cache, is_insert=False)
indices_to_remove.add(i)
if self.scheduler.metrics_reporter.enable_metrics:
self.scheduler.metrics_collector.increment_transfer_failed_reqs()
continue
elif poll == KVPoll.Success:
should_remove = self._commit_transfer_to_req(decode_req)
if should_remove:
indices_to_remove.add(i)
# Check if request was aborted due to corruption
if isinstance(decode_req.req.finished_reason, FINISH_ABORT):
self.scheduler.output_streamer.stream_output(
[decode_req.req],
decode_req.req.return_logprob,
)
if self.scheduler.enable_hisparse:
self.scheduler.hisparse_coordinator.request_finished(
decode_req.req
)
release_kv_cache(
decode_req.req, self.tree_cache, is_insert=False
)
if self.scheduler.metrics_reporter.enable_metrics:
self.scheduler.metrics_collector.increment_transfer_failed_reqs()
else:
transferred_reqs.append(decode_req.req)
elif poll in [
KVPoll.Bootstrapping,
KVPoll.WaitingForInput,
KVPoll.Transferring,
]:
pass
else:
raise ValueError(f"Unexpected poll case: {poll}")
for i in indices_to_remove:
if self.enable_staging and self.staging_handler.is_staging_room(
self.queue[i].req.bootstrap_room
):
self.staging_handler.unregister_decode_req(
self.queue[i].req.bootstrap_room
)
idx = self.queue[i].metadata_buffer_index
assert idx != -1
self.req_to_metadata_buffer_idx_allocator.free(idx)
self.queue = [
entry for i, entry in enumerate(self.queue) if i not in indices_to_remove
]
return transferred_reqs
class SchedulerDisaggregationDecodeMixin:
@torch.no_grad()
def event_loop_normal_disagg_decode(self: Scheduler):
"""A normal scheduler loop for decode worker in disaggregation mode."""
while True:
# Receive requests
recv_reqs = self.request_receiver.recv_requests()
self.process_input_requests(recv_reqs)
self.process_decode_queue()
if self._engine_paused:
continue
# Get the next batch to run
batch = self.get_next_disagg_decode_batch_to_run()
self.cur_batch = batch
# Launch the current batch
if batch:
result = self.run_batch(batch)
self.process_batch_result(batch, result)
else:
# When the server is idle, do self-check and re-init some states
self.on_idle()
# Update last_batch
self.last_batch = batch
@torch.no_grad()
def event_loop_overlap_disagg_decode(self: Scheduler):
self.result_queue = deque()
self.last_batch: Optional[ScheduleBatch] = None
while True:
# Receive requests
recv_reqs = self.request_receiver.recv_requests()
self.process_input_requests(recv_reqs)
self.process_decode_queue()
if self._engine_paused:
continue
# Get the next batch to run
batch = self.get_next_disagg_decode_batch_to_run()
self.cur_batch = batch
# Launch the current batch
if batch:
batch_result = self.run_batch(batch)
self.result_queue.append((batch.copy(), batch_result))
else:
batch_result = None
# Process the last batch
if self.last_batch:
tmp_batch, tmp_result = self.result_queue.popleft()
self.process_batch_result(tmp_batch, tmp_result)
elif batch is None:
self.on_idle()
# Run sample of the current batch
# It depends on the result of the last batch (e.g., grammar), so we run it after the last batch is processed.
self.launch_batch_sample_if_needed(batch_result)
# Update last_batch
self.last_batch = batch
def _run_batch_prebuilt(
self: Scheduler, batch: ScheduleBatch
) -> GenerationBatchResult:
if batch.inner_idle_batch is not None:
idle_batch = batch.inner_idle_batch
# Reset the inner idle batch to avoid reusing it.
batch.inner_idle_batch = None
return self.run_batch(idle_batch)
return GenerationBatchResult()
def get_next_disagg_decode_batch_to_run(
self: Scheduler,
) -> Optional[ScheduleBatch]:
"""Process prebuilt batch and schedule the next decode batch."""
# Process pending prebuilt batch: output processing + filter + merge
new_prebuilt_batch = self.get_new_prebuilt_batch()
if new_prebuilt_batch:
assert self.chunked_req is None
self.batch_result_processor.process_batch_result_prebuilt(
new_prebuilt_batch
)
new_prebuilt_batch.filter_batch()
if not new_prebuilt_batch.is_empty():
if self.running_batch.is_empty():
self.running_batch = new_prebuilt_batch
if self.enable_hisparse:
self.running_batch.hisparse_coordinator = (
self.hisparse_coordinator
)
else:
self.running_batch.merge_batch(new_prebuilt_batch)
# Schedule decode batch
if self.running_batch.is_empty():
ret = None
else:
self.running_batch = self.update_running_batch(self.running_batch)
ret = self.running_batch if not self.running_batch.is_empty() else None
ret = self.dp_attn_adapter.maybe_prepare_mlp_sync_batch(ret)
if ret:
set_schedule_time_batch(ret)
return ret
def get_new_prebuilt_batch(self: Scheduler) -> Optional[ScheduleBatch]:
"""Create a schedulebatch for fake completed prefill"""
if self.grammar_manager.has_waiting_grammars():
ready_grammar_requests = self.grammar_manager.get_ready_grammar_requests()
for req in ready_grammar_requests:
self._add_request_to_queue(req)
if len(self.waiting_queue) == 0:
return None
if self.enable_priority_scheduling:
self.policy.calc_priority(self.waiting_queue, self.running_batch)
curr_batch_size = self.running_batch.batch_size()
batch_size = min(self.req_to_token_pool.size, self.max_running_requests)
num_not_used_batch = batch_size - curr_batch_size
# pop req from waiting queue
can_run_list: List[Req] = []
waiting_queue: List[Req] = []
for i in range(len(self.waiting_queue)):
req = self.waiting_queue[i]
# we can only add at least `num_not_used_batch` new batch to the running queue
if i < num_not_used_batch:
can_run_list.append(req)
# Decode-radix path: do NOT re-match prefix here.
# `pop_preallocated` already took a tree snapshot and used it
# to (1) pre-allocate KV, (2) choose delta pages for transfer,
# and (3) set cache_protected_len/last_node for correct frees.
# Re-matching now can observe a newer tree (other reqs may have
# inserted the same prefix) and overwrite cache_protected_len,
# making `cache_unfinished_req` free the wrong range (leak).
# Non-radix decode keeps the original behavior.
tree_cache = (
None
if self.server_args.disaggregation_decode_enable_radix_cache
else self.tree_cache
)
req.init_next_round_input(tree_cache)
# Truncate fill_ids to kv_committed_len so cache_unfinished_req
# only sees committed KV (fill_ids includes one uncommitted token).
if req.kv_committed_len is not None:
req.fill_ids = req.fill_ids[: req.kv_committed_len]
req.set_extend_input_len(
len(req.fill_ids) - len(req.prefix_indices)
)
else:
waiting_queue.append(req)
self.waiting_queue = waiting_queue
if len(can_run_list) == 0:
return None
set_time_batch(can_run_list, "set_forward_entry_time")
# construct a schedule batch with those requests and mark as decode
new_batch = ScheduleBatch.init_new(
can_run_list,
self.req_to_token_pool,
self.token_to_kv_pool_allocator,
self.tree_cache,
self.model_config,
self.enable_overlap,
self.spec_algorithm,
)
# construct fake completed prefill
new_batch.prepare_for_prebuilt()
new_batch.process_prebuilt(self.server_args, self.future_map)
return new_batch
def process_decode_queue(self: Scheduler):
if self.server_args.disaggregation_decode_enable_offload_kvcache:
self.decode_offload_manager.check_offload_progress()
# try to resume retracted requests if there are enough space for another `num_reserved_decode_tokens` decode steps
resumed_reqs = self.disagg_decode_prealloc_queue.resume_retracted_reqs()
self.waiting_queue.extend(resumed_reqs)
if len(self.disagg_decode_prealloc_queue.retracted_queue) > 0:
# if there are still retracted requests, we do not allocate new requests
return
if not hasattr(self, "polling_count"):
self.polling_count = 0
self.polling_interval = (
self.server_args.disaggregation_decode_polling_interval
)
self.polling_count = (self.polling_count + 1) % self.polling_interval
if self.polling_count % self.polling_interval == 0:
req_conns, _ = self.disagg_decode_prealloc_queue.pop_preallocated()
self.disagg_decode_transfer_queue.extend(req_conns)
transferred_reqs = (
self.disagg_decode_transfer_queue.pop_transferred()
) # the requests which kv has arrived
if self.enable_hisparse:
for req in transferred_reqs:
# Direct-to-host: KV data already in host pool, skip staging
self.hisparse_coordinator.admit_request_direct(req)
self.waiting_queue.extend(transferred_reqs)
else:
self.waiting_queue.extend(transferred_reqs)