Record a process's placement at publish, not at group build (#40071)

python/sglang/benchmark/one_batch.py

@@ -93,10 +93,12 @@ from sglang.srt.model_executor.cuda_graph_config import (
 from sglang.srt.model_executor.forward_batch_info import ForwardBatch
 from sglang.srt.model_executor.model_runner import ModelRunner
 from sglang.srt.runtime_context import (
+    SpawnRanks,
     get_model,
     get_parallel,
     get_schedule,
     publish,
+    spawn_world_rank,
 )
 from sglang.srt.sampling.sampling_params import SamplingParams
 from sglang.srt.server_args import PortArgs, ServerArgs
@@ -707,7 +709,15 @@ def correctness_test(
     gpu_id,
     tp_rank,
 ):
-    publish(server_args, role="scheduler")
+    # With the placement this process was spawned with, so a rank read here
+    # does not need a process group -- the same bundle the runner is handed.
+    publish(
+        server_args,
+        role="scheduler",
+        ranks=SpawnRanks(
+            world_rank=spawn_world_rank(server_args, tp_rank=tp_rank, pp_rank=0)
+        ),
+    )
 
     # Configure the logger
     configure_logger(server_args, prefix=f" TP{tp_rank}")
@@ -912,7 +922,13 @@ def latency_test(
     cfg = resolving_view(server_args)
     # `main` runs this inline for tp_size == 1 and spawns it per rank otherwise;
     # a spawned child arrives with nothing published.
-    publish(server_args, role="scheduler")
+    publish(
+        server_args,
+        role="scheduler",
+        ranks=SpawnRanks(
+            world_rank=spawn_world_rank(server_args, tp_rank=tp_rank, pp_rank=0)
+        ),
+    )
     initialize_moe_config()
     initialize_fp8_gemm_config()
     initialize_fp4_gemm_config()

python/sglang/srt/constrained/grammar_manager.py

@@ -14,7 +14,7 @@ from sglang.srt.constrained.base_grammar_backend import (
 from sglang.srt.constrained.reasoner_grammar_backend import ReasonerGrammarObject
 from sglang.srt.distributed.communication_tags import P2PTag
 from sglang.srt.environ import envs
-from sglang.srt.runtime_context import get_serving
+from sglang.srt.runtime_context import get_parallel, get_serving
 from sglang.srt.sampling.sampling_params import (
     get_request_reasoning_end_token_ids,
 )
@@ -53,8 +53,8 @@ class GrammarManager:
         self.grammar_sync_size = scheduler.dp_tp_group.world_size
         self.grammar_sync_entry = scheduler.dp_tp_group.first_rank
         self.is_grammar_sync_entry = scheduler.dp_tp_group.is_first_rank
-        self.pp_rank = scheduler.ps.pp_rank
+        self.pp_rank = get_parallel().pp_rank
-        self.pp_size = scheduler.ps.pp_size
+        self.pp_size = get_parallel().pp_size
         self.pp_group = scheduler.pp_group
         self.grammar_pp_sync_work_list = []
 

python/sglang/srt/disaggregation/decode.py

@@ -393,7 +393,7 @@ class DecodePreallocQueue(DecodeHiCachePreallocMixin):
         self.bootstrap_port = bootstrap_port
         self.max_total_num_tokens = max_total_num_tokens
         self.pp_rank = pp_rank
-        self.pp_size = scheduler.ps.pp_size
+        self.pp_size = get_parallel().pp_size
         self.num_reserved_decode_tokens = num_reserved_decode_tokens
         self.transfer_backend = transfer_backend
         # Queue for requests pending pre-allocation

python/sglang/srt/disaggregation/prefill.py

@@ -997,7 +997,7 @@ class SchedulerDisaggregationPrefillMixin:
                     KVPoll.Failed,
                 ):
                     logger.warning_once(
-                        f"PP rank {self.ps.pp_rank}: unexpected poll state {poll} for rid {req.rid} "
+                        f"PP rank {get_parallel().pp_rank}: unexpected poll state {poll} for rid {req.rid} "
                         f"from consensus; treating as undone",
                     )
                     undone_reqs.append(req)
@@ -1077,7 +1077,7 @@ class SchedulerDisaggregationPrefillMixin:
     ) -> Optional[Exception]:
         """Conclude an inflight request whose KV transfer failed."""
         error_message = (
-            f"Prefill transfer failed for request rank={self.ps.tp_rank} "
+            f"Prefill transfer failed for request rank={get_parallel().tp_rank} "
             f"{req.rid=} {req.bootstrap_room=}"
         )
         exc: Optional[Exception] = None
@@ -1142,7 +1142,7 @@ class SchedulerDisaggregationPrefillMixin:
     def handle_bootstrap_failure(self: Scheduler, req: Req) -> None:
         self.clear_pending_chunk_send(req)
         error_message = (
-            f"Prefill bootstrap failed for request rank={self.ps.tp_rank} "
+            f"Prefill bootstrap failed for request rank={get_parallel().tp_rank} "
             f"{req.rid=} {req.bootstrap_room=}"
         )
         is_propagated = False

python/sglang/srt/distributed/bootstrap.py

@@ -99,6 +99,7 @@ def init_torch_distributed(
             )
 
         # Only initialize the distributed environment on the target model worker.
+        # This builds the groups behind the context's live group-handle reads.
         _init_parallel_groups(
             backend=backend,
             dist_init_method=dist_init_method,

python/sglang/srt/distributed/parallel_state.py

@@ -3029,6 +3029,13 @@ def patch_pipeline_parallel_group(pp_group: GroupCoordinator):
     global _PP
     _PP = pp_group
     try:
+        # `pp_size` is a configured leaf: unlike the rank and the handle it
+        # does not follow the group being swapped, so the scope has to name it.
+        with get_parallel().override(
+            pp_size=pp_group.world_size,
+            pp_rank=pp_group.rank_in_group,
+            pp_group=pp_group,
+        ):
             yield
     finally:
         _PP_STATE_PATCHED = False

python/sglang/srt/layers/deep_gemm_wrapper/compile_utils.py

@@ -509,7 +509,7 @@ def pp_parallel_deep_gemm_warmup(runner) -> None:
     logger.info(
         "PP-parallel DeepGEMM warmup start "
         "(pp_rank=%d, tp_rank=%d, batch_sizes=%s, disagg=%s).",
-        model_runner.ps.pp_rank,
+        get_parallel().pp_rank,
         model_runner.ps.tp_rank,
         batch_sizes,
         disagg_mode,
@@ -538,5 +538,5 @@ def pp_parallel_deep_gemm_warmup(runner) -> None:
     logger.info(
         "PP-parallel DeepGEMM warmup done in %.2fs (pp_rank=%d).",
         time.perf_counter() - t0,
-        model_runner.ps.pp_rank,
+        get_parallel().pp_rank,
     )

python/sglang/srt/layers/dp_attention.py

@@ -27,6 +27,7 @@ from sglang.srt.distributed.device_communicators.pynccl_allocator import (
 )
 from sglang.srt.environ import envs
 from sglang.srt.runtime_context import (
+    derive_attention_ranks,
     derive_attention_widths,
     get_device,
     get_exec,
@@ -349,15 +350,12 @@ def compute_dp_attention_world_info(
         dp_size=dp_size,
         enable_dp_attention=enable_dp_attention,
     )
-    attn_tp_rank = tp_rank % attn_tp_size
+    attn_tp_rank, attn_dp_rank = derive_attention_ranks(
-
+        tp_rank=tp_rank,
-    if not enable_dp_attention:
+        attn_tp_size=attn_tp_size,
-        attn_dp_rank = 0
+        attn_cp_size=attn_cp_size,
-    else:
+        enable_dp_attention=enable_dp_attention,
-        # Rank layout is (dp, cp, tp) where tp is the fastest-changing dim:
+    )
-        # tp_rank = (attn_dp_rank * attn_cp_size + attn_cp_rank) * attn_tp_size + attn_tp_rank
-        attn_dp_rank = tp_rank // (attn_tp_size * attn_cp_size)
-
     return attn_tp_rank, attn_tp_size, attn_dp_rank, attn_dp_size
 
 

python/sglang/srt/managers/scheduler.py

@@ -29,6 +29,7 @@ from http import HTTPStatus
 from typing import TYPE_CHECKING, Any, Deque, Dict, List, Optional, Set, Tuple, Union
 
 from sglang.srt.runtime_context import (
+    SpawnRanks,
     attention_backends,
     get_context,
     get_device,
@@ -44,6 +45,7 @@ from sglang.srt.runtime_context import (
     get_serving,
     get_spec,
     publish,
+    spawn_world_rank,
 )
 
 from sglang.srt.utils.common import suppress_noisy_warnings  # isort: skip
@@ -595,9 +597,9 @@ class Scheduler(
             enable_metrics=get_observability().enable_metrics,
             enable_kv_cache_events=bool(
                 get_observability().kv_events_config
-                and self.ps.pp_rank == 0
+                and get_parallel().pp_rank == 0
-                and self.ps.attn_tp_rank == 0
+                and get_parallel().attn_tp_rank == 0
-                and self.ps.attn_cp_rank == 0
+                and get_parallel().attn_cp_rank == 0
             ),
             ps=self.ps,
             tp_group=self.tp_group,
@@ -759,8 +761,8 @@ class Scheduler(
             return
 
         rank = (
-            self.ps.dp_rank
+            get_parallel().dp_rank
-            if self.ps.dp_rank is not None
+            if get_parallel().dp_rank is not None
             else self.tp_group.rank_in_group
         )
         logger.info("HCCL DP prewarm start: rank=%s", rank)
@@ -775,10 +777,10 @@ class Scheduler(
         if _is_npu:
             from sglang.srt.hardware_backend.npu.utils import init_zbal
 
-            if self.ps.pp_size > 1:
+            if get_parallel().pp_size > 1:
                 logger.error("only zbal mix mode support pp_size > 1!")
             init_zbal(
-                self.ps.tp_size, self.ps.gpu_id, self.ps.tp_rank
+                get_parallel().tp_size, self.ps.gpu_id, get_parallel().tp_rank
             )  # only switch allocator if is mix mode
 
     def init_model_config(self):
@@ -811,9 +813,9 @@ class Scheduler(
 
     def init_ipc_channels(self, port_args: PortArgs):
         is_rank_zero = (
-            self.ps.pp_rank == 0
+            get_parallel().pp_rank == 0
-            and self.ps.attn_tp_rank == 0
+            and get_parallel().attn_tp_rank == 0
-            and self.ps.attn_cp_rank == 0
+            and get_parallel().attn_cp_rank == 0
         )
         self.ipc_channels = SchedulerIpcChannels.create(
             port_args=port_args,
@@ -824,7 +826,7 @@ class Scheduler(
             skip_tokenizer_init=self.skip_tokenizer_init,
             metrics_enabled=get_observability().enable_metrics
             and (
-                self.ps.attn_tp_rank == 0
+                get_parallel().attn_tp_rank == 0
                 or get_observability().enable_metrics_for_all_schedulers
             ),
             enable_scripted_runtime=envs.SGLANG_TEST_SCRIPTED_RUNTIME.get(),
@@ -837,7 +839,7 @@ class Scheduler(
             return
 
         self.recv_from_tokenizer = self.ipc_channels.recv_from_tokenizer
-        dp_rank = self.ps.dp_rank if self.ps.dp_rank is not None else 0
+        dp_rank = get_parallel().dp_rank if get_parallel().dp_rank is not None else 0
         try:
             self.load_snapshot_writer = create_load_snapshot_writer(
                 port_args,
@@ -850,9 +852,9 @@ class Scheduler(
 
     def init_idle_sleeper(self) -> None:
         if (
-            self.ps.pp_rank == 0
+            get_parallel().pp_rank == 0
-            and self.ps.attn_tp_rank == 0
+            and get_parallel().attn_tp_rank == 0
-            and self.ps.attn_cp_rank == 0
+            and get_parallel().attn_cp_rank == 0
             and get_device().sleep_on_idle
         ):
             self.idle_sleeper = IdleSleeper(
@@ -1032,8 +1034,8 @@ class Scheduler(
 
         if (
             envs.SGLANG_ENABLE_PP_SPEC.get()
-            and self.ps.pp_size > 1
+            and get_parallel().pp_size > 1
-            and self.ps.pp_rank != self.ps.pp_size - 1
+            and get_parallel().pp_rank != get_parallel().pp_size - 1
         ):
             # PP+spec: the draft model (MTP layer) needs final hidden states and
             # the lm_head, both of which live on the last PP stage only.
@@ -1130,7 +1132,7 @@ class Scheduler(
         # Match run_batch / _pp_launch_batch so warmup allocations stay reusable.
         forward_stream = (
             model_runner.forward_stream
-            if self.enable_overlap or self.ps.pp_size > 1 or use_mlx()
+            if self.enable_overlap or get_parallel().pp_size > 1 or use_mlx()
             else self.schedule_stream
         )
         with device_module.stream(forward_stream):
@@ -1208,7 +1210,7 @@ class Scheduler(
             get_context().override(
                 "scheduler.pp_max_micro_batch_size_default",
                 pp_max_micro_batch_size=max(
-                    self.max_running_requests // self.ps.pp_size, 1
+                    self.max_running_requests // get_parallel().pp_size, 1
                 ),
             )
 
@@ -1239,7 +1241,7 @@ class Scheduler(
         self.startup_available_gpu_memory_gb = get_available_gpu_memory(
             self.device, self.ps.gpu_id, empty_cache=False
         )
-        if self.ps.tp_rank == 0:
+        if get_parallel().tp_rank == 0:
             logger.info(
                 f"max_total_num_tokens={self.max_total_num_tokens}, "
                 f"chunked_prefill_size={get_schedule().chunked_prefill_size}, "
@@ -1344,7 +1346,7 @@ class Scheduler(
     def maybe_init_dynamic_chunk_sizer(self) -> None:
         """Profile a PP prefill latency model that sizes chunks per stage."""
         self.dynamic_chunk_sizer: Optional[DynamicChunkSizer] = None
-        if not (get_schedule().enable_dynamic_chunking and self.ps.pp_size > 1):
+        if not (get_schedule().enable_dynamic_chunking and get_parallel().pp_size > 1):
             return
         sizer = DynamicChunkSizer(
             model_runner=self.tp_worker.model_runner,
@@ -1359,7 +1361,7 @@ class Scheduler(
             device=self.device,
             pp_group=self.pp_group,
             world_group=self.world_group,
-            pp_rank=self.ps.pp_rank,
+            pp_rank=get_parallel().pp_rank,
         )
         if sizer.profile_and_fit():
             self.dynamic_chunk_sizer = sizer
@@ -1422,7 +1424,7 @@ class Scheduler(
             else:
                 self.prefill_delayer = PrefillDelayer(
                     dp_size=self.ps.dp_size,
-                    attn_tp_size=self.ps.attn_tp_size,
+                    attn_tp_size=get_parallel().attn_tp_size,
                     cpu_group=self.tp_cpu_group,
                     device_group=self.tp_group.device_group,
                     metrics_collector=(
@@ -1433,7 +1435,7 @@ class Scheduler(
                     max_delay_passes=get_schedule().prefill_delayer_max_delay_passes,
                     token_usage_low_watermark=get_schedule().prefill_delayer_token_usage_low_watermark,
                     device=self.tp_group.device,
-                    debug_log_enabled=self.ps.attn_tp_rank == 0,
+                    debug_log_enabled=get_parallel().attn_tp_rank == 0,
                 )
 
         # NOTE: preemption is enabled by default for priority scheduling.
@@ -1464,7 +1466,7 @@ class Scheduler(
         # Init recv skipper and input blocker
         self.recv_skipper = SchedulerRecvSkipper.maybe_create()
         self.input_blocker = (
-            SchedulerInputBlocker(noop=self.ps.attn_tp_rank != 0)
+            SchedulerInputBlocker(noop=get_parallel().attn_tp_rank != 0)
             if get_bool_env_var("SGLANG_ENABLE_COLOCATED_BATCH_GEN")
             else None
         )
@@ -1553,7 +1555,7 @@ class Scheduler(
             self.disagg_decode_transfer_queue = DecodeTransferQueue(
                 gloo_group=self.attn_tp_cpu_group,
                 req_to_metadata_buffer_idx_allocator=self.req_to_metadata_buffer_idx_allocator,
-                tp_rank=self.ps.tp_rank,
+                tp_rank=get_parallel().tp_rank,
                 metadata_buffers=self.disagg_metadata_buffers,
                 scheduler=self,
                 tree_cache=self.tree_cache,
@@ -1570,13 +1572,13 @@ class Scheduler(
                 transfer_queue=self.disagg_decode_transfer_queue,
                 tree_cache=self.tree_cache,
                 gloo_group=self.attn_tp_cpu_group,
-                tp_rank=self.ps.tp_rank,
+                tp_rank=get_parallel().tp_rank,
-                tp_size=self.ps.tp_size,
+                tp_size=get_parallel().tp_size,
                 dp_size=get_parallel().dp_size,
                 gpu_id=self.ps.gpu_id,
                 bootstrap_port=get_disagg().disaggregation_bootstrap_port,
                 max_total_num_tokens=self.max_total_num_tokens,
-                pp_rank=self.ps.pp_rank,
+                pp_rank=get_parallel().pp_rank,
                 num_reserved_decode_tokens=get_disagg().num_reserved_decode_tokens,
                 transfer_backend=self.transfer_backend,
             )
@@ -1602,16 +1604,16 @@ class Scheduler(
                 draft_token_to_kv_pool=draft_token_to_kv_pool,
                 req_to_metadata_buffer_idx_allocator=self.req_to_metadata_buffer_idx_allocator,
                 metadata_buffers=self.disagg_metadata_buffers,
-                tp_rank=self.ps.tp_rank,
+                tp_rank=get_parallel().tp_rank,
-                tp_size=self.ps.tp_size,
+                tp_size=get_parallel().tp_size,
                 gpu_id=self.ps.gpu_id,
                 bootstrap_port=get_disagg().disaggregation_bootstrap_port,
                 gloo_group=self.attn_tp_cpu_group,
                 max_total_num_tokens=self.max_total_num_tokens,
                 scheduler=self,
                 scheduler_stage_metrics=self.scheduler_stage_metrics,
-                pp_rank=self.ps.pp_rank,
+                pp_rank=get_parallel().pp_rank,
-                pp_size=self.ps.pp_size,
+                pp_size=get_parallel().pp_size,
                 transfer_backend=self.transfer_backend,
             )
             # The prefill requests that are in the middle of kv sending
@@ -1638,8 +1640,8 @@ class Scheduler(
                 self.server_args,
                 dtype=self.model_config.dtype,
                 hf_config=self.model_config.hf_config,
-                pp_rank=self.ps.pp_rank,
+                pp_rank=get_parallel().pp_rank,
-                tp_rank=self.ps.tp_rank,
+                tp_rank=get_parallel().tp_rank,
                 tp_group=self.tp_group,
                 scheduler=self,
             )
@@ -1895,7 +1897,9 @@ class Scheduler(
 
         if self.device == "cpu":
             self.schedule_stream.synchronize = lambda: None  # No-op for CPU
-        elif (is_cuda() or _is_hip) and (self.enable_overlap or self.ps.pp_size > 1):
+        elif (is_cuda() or _is_hip) and (
+            self.enable_overlap or get_parallel().pp_size > 1
+        ):
             # CUDA/HIP streams come from a fixed round-robin pool. Redraw if this
             # stream aliases forward_stream, which would eliminate scheduler
             # overlap. Only CUDA/HIP streams expose a ``cuda_stream`` handle;
@@ -2090,9 +2094,9 @@ class Scheduler(
         """
         local_reqs = []
         if (
-            self.ps.pp_rank == 0
+            get_parallel().pp_rank == 0
-            and self.ps.attn_tp_rank == 0
+            and get_parallel().attn_tp_rank == 0
-            and self.ps.attn_cp_rank == 0
+            and get_parallel().attn_cp_rank == 0
         ):
             local_reqs = self._poll_timeout_aborts()
         recv_reqs = self.request_receiver.recv_requests(local_reqs=local_reqs)
@@ -2290,9 +2294,9 @@ class Scheduler(
         and with it the server-process duties a Python ``TokenizerManager``
         would otherwise own (e.g. serving the PD KV bootstrap registry)."""
         return envs.SGLANG_RUST_SERVER.get() and (
-            self.ps.pp_rank == 0
+            get_parallel().pp_rank == 0
-            and self.ps.attn_tp_rank == 0
+            and get_parallel().attn_tp_rank == 0
-            and self.ps.attn_cp_rank == 0
+            and get_parallel().attn_cp_rank == 0
         )
 
     def maybe_init_rust_server(self) -> None:
@@ -2417,10 +2421,10 @@ class Scheduler(
         self.kv_events_publisher = SchedulerKvEventsPublisher(
             kv_events_config=get_observability().kv_events_config,
             ps=self.ps,
-            attn_tp_rank=self.ps.attn_tp_rank,
+            attn_tp_rank=get_parallel().attn_tp_rank,
-            attn_cp_rank=self.ps.attn_cp_rank,
+            attn_cp_rank=get_parallel().attn_cp_rank,
             attn_dp_rank=self.ps.attn_dp_rank,
-            dp_rank=self.ps.dp_rank,
+            dp_rank=get_parallel().dp_rank,
             tree_cache=self.tree_cache,
             send_metrics_from_scheduler=self.ipc_channels.send_metrics_from_scheduler,
             max_running_requests=self.max_running_requests,
@@ -3398,7 +3402,7 @@ class Scheduler(
 
         if (timeout_s := envs.SGLANG_REQ_RUNNING_TIMEOUT.get()) > 0:
             deadline = time.perf_counter() - timeout_s
-            if self.ps.pp_size == 1:
+            if get_parallel().pp_size == 1:
                 inflight_batches = [self.running_batch, self.last_batch]
             else:
                 inflight_batches = [*self.running_mbs, *self.mbs]
@@ -4460,7 +4464,7 @@ class Scheduler(
                 batch.input_ids = None
                 self._copy_auxiliary_output_to_cpu(batch, batch_result)
             elif not batch.spec_algorithm.is_none():
-                is_verify_round = self.ps.pp_size > 1 and not (
+                is_verify_round = get_parallel().pp_size > 1 and not (
                     batch.forward_mode.is_extend() or batch.is_extend_in_batch
                 )
                 # The relayed tree is what the requests carry between rounds;
@@ -4548,7 +4552,10 @@ class Scheduler(
                     # Only the last PP rank owns real results requiring D2H; other ranks
                     # consume device tensors rebuilt from the output ring.
                     batch_result.copy_done = self.device_module.Event()
-                    if batch_result.has_sampled_token_ids and self.ps.pp_size == 1:
+                    if (
+                        batch_result.has_sampled_token_ids
+                        and get_parallel().pp_size == 1
+                    ):
                         batch_result.copy_to_cpu(
                             return_logprob=batch.return_logprob,
                             return_hidden_states=batch.return_hidden_states,
@@ -4685,7 +4692,7 @@ class Scheduler(
         ):
             return
         # PP transports the device output to the first rank before copying it.
-        if self.ps.pp_size > 1:
+        if get_parallel().pp_size > 1:
             return
         if result.copy_done is not None:
             raise RuntimeError(
@@ -5024,7 +5031,7 @@ class Scheduler(
         return idle
 
     def _pp_microbatches_drained(self) -> bool:
-        if self.ps.pp_size == 1:
+        if get_parallel().pp_size == 1:
             return True
         return all(x.is_empty() for x in self.running_mbs) and all(
             mb is None or mb.is_empty() for mb in self.mbs
@@ -5265,10 +5272,10 @@ class Scheduler(
                 if_success = False
                 break
             elif k == "pp_max_micro_batch_size" and (
-                v > self.max_running_requests // self.ps.pp_size or v < 1
+                v > self.max_running_requests // get_parallel().pp_size or v < 1
             ):
                 logging.warning(
-                    f"Updating {k} to {v} is rejected because it is out of the valid range [1, {self.max_running_requests // self.ps.pp_size}]."
+                    f"Updating {k} to {v} is rejected because it is out of the valid range [1, {self.max_running_requests // get_parallel().pp_size}]."
                 )
                 if_success = False
                 break
@@ -5382,7 +5389,7 @@ class Scheduler(
         )
 
     def collect_inflight_reqs(self) -> Set[Req]:
-        if self.ps.pp_size == 1:
+        if get_parallel().pp_size == 1:
             inflight_batches = [self.running_batch, self.last_batch]
         else:
             inflight_batches = [*self.running_mbs, *self.mbs]
@@ -5472,7 +5479,7 @@ class Scheduler(
 
                     if hasattr(req.disagg_kv_sender, "abort"):
                         req.disagg_kv_sender.abort()
-                    if self.ps.pp_size > 1:
+                    if get_parallel().pp_size > 1:
                         prepare_abort(req, "Aborted by AbortReq.")
 
             # Abort in-flight requests
@@ -5488,7 +5495,7 @@ class Scheduler(
                 if recv_req.abort_all or decode_req.req.rid.startswith(recv_req.rid):
                     logger.debug(f"Abort prealloc queue request. {decode_req.req.rid=}")
                     decode_req.kv_receiver.abort()
-                    if self.ps.pp_size > 1:
+                    if get_parallel().pp_size > 1:
                         prepare_abort(decode_req.req, "Aborted by AbortReq.")
 
             # Abort requests waiting for kvcache to release tree cache
@@ -5821,7 +5828,11 @@ class Scheduler(
         output = self.session_controller.open(recv_req)
         if output.success and self.enable_session_radix_cache:
             self.tree_cache.open_radix_session(recv_req.session_id)
-        if self.ps.pp_rank == 0 and self.ps.tp_rank == 0 and self.ps.attn_cp_rank == 0:
+        if (
+            get_parallel().pp_rank == 0
+            and get_parallel().tp_rank == 0
+            and get_parallel().attn_cp_rank == 0
+        ):
             return output
         return None
 
@@ -5922,6 +5933,20 @@ def _dispatch_event_loop_once(scheduler: Scheduler):
             scheduler.event_loop_normal_disagg_decode()
 
 
+def resolve_spawn_dp_rank(dp_rank: Optional[int]) -> Optional[int]:
+    """The `dp_rank` this process was spawned with, in either of its two forms.
+
+    A router does not pass it as an argument, it sets `SGLANG_DP_RANK`. Both
+    forms are the launcher naming this process's place, so both have to be in
+    hand before `publish` records the placement -- resolving one of them after
+    would leave the context answering `None` for a process that has a rank.
+    """
+    if dp_rank is None and "SGLANG_DP_RANK" in os.environ:
+        # [For Router] if env var "SGLANG_DP_RANK" exist, set dp_rank to the value of the env var
+        return int(os.environ["SGLANG_DP_RANK"])
+    return dp_rank
+
+
 def configure_scheduler_process(
     server_args: ServerArgs,
     gpu_id: int,
@@ -5934,18 +5959,15 @@ def configure_scheduler_process(
     display_tp_rank: Optional[int] = None,
     display_dp_rank: Optional[int] = None,
     display_moe_ep_rank: Optional[int] = None,
-) -> Optional[int]:
+) -> None:
     """Configure scheduler worker logging and process title.
 
-    display_* ranks are cosmetic; runtime ranks stay local.
+    display_* ranks are cosmetic; runtime ranks stay local. `dp_rank` arrives
+    already resolved -- see `resolve_spawn_dp_rank`.
     """
     kill_itself_when_parent_died()
 
     # Generate the logger prefix
-    if dp_rank is None and "SGLANG_DP_RANK" in os.environ:
-        # [For Router] if env var "SGLANG_DP_RANK" exist, set dp_rank to the value of the env var
-        dp_rank = int(os.environ["SGLANG_DP_RANK"])
-
     shown_dp = display_dp_rank if display_dp_rank is not None else dp_rank
     shown_tp = display_tp_rank if display_tp_rank is not None else tp_rank
     shown_moe_ep = (
@@ -5987,8 +6009,6 @@ def configure_scheduler_process(
         if numa_node is not None:
             numa_bind_to_node(numa_node)
 
-    return dp_rank
-
 
 def run_scheduler_process(
     server_args: ServerArgs,
@@ -6007,9 +6027,20 @@ def run_scheduler_process(
 ):
     # Load plugins so hooks can override Scheduler and its dependencies.
     load_plugins()
-    # Publish before anything in this process reads configuration.
+    dp_rank = resolve_spawn_dp_rank(dp_rank)
-    publish(server_args, role="scheduler")
+    # Publish before anything in this process reads configuration, with the
-    dp_rank = configure_scheduler_process(
+    # placement the launcher decided: from here on a rank read is answered
+    # without a process group, which is what every reader needs before
+    # `init_torch_distributed` has run.
+    publish(
+        server_args,
+        role="scheduler",
+        ranks=SpawnRanks(
+            world_rank=spawn_world_rank(server_args, tp_rank=tp_rank, pp_rank=pp_rank),
+            dp_rank=dp_rank,
+        ),
+    )
+    configure_scheduler_process(
         server_args,
         gpu_id,
         tp_rank,

python/sglang/srt/managers/scheduler_components/dp_attn.py

@@ -548,8 +548,8 @@ class SchedulerDPAttnAdapter:
             local_batch,
             model_runner=self.model_runner,
             dp_size=get_parallel().dp_size,
-            attn_tp_size=self.ps.attn_tp_size,
+            attn_tp_size=get_parallel().attn_tp_size,
-            attn_cp_size=self.ps.attn_cp_size,
+            attn_cp_size=get_parallel().attn_cp_size,
             tp_group=self.tp_group,
             get_idle_batch=self.get_idle_batch,
             disable_cuda_graph=cuda_graph_fully_disabled(),

python/sglang/srt/managers/scheduler_components/kv_events_publisher.py

@@ -19,6 +19,7 @@ from sglang.srt.disaggregation.kv_events import (
     select_kv_publisher_dp_rank,
 )
 from sglang.srt.managers.io_struct import hook_custom_types, sock_send
+from sglang.srt.runtime_context import get_parallel
 
 if TYPE_CHECKING:
     from sglang.srt.distributed.parallel_state_wrapper import ParallelState
@@ -68,7 +69,7 @@ class SchedulerKvEventsPublisher:
             self.kv_event_publisher = EventPublisherFactory.create(
                 kv_events_config,
                 select_kv_publisher_dp_rank(
-                    self.ps.attn_dp_size, self.ps.attn_dp_rank, self.ps.dp_rank
+                    self.ps.attn_dp_size, self.ps.attn_dp_rank, get_parallel().dp_rank
                 ),
             )
 
@@ -87,7 +88,7 @@ class SchedulerKvEventsPublisher:
         kv_metrics.gpu_cache_usage_perc = self.get_stats().token_usage
         kv_metrics.gpu_prefix_cache_hit_rate = self.get_stats().cache_hit_rate
         kv_metrics.data_parallel_rank = (
-            self.ps.dp_rank if self.ps.dp_rank is not None else 0
+            get_parallel().dp_rank if get_parallel().dp_rank is not None else 0
         )
 
         if not self.send_metrics_from_scheduler.closed:

python/sglang/srt/managers/scheduler_components/load_inquirer.py

@@ -14,7 +14,7 @@ from sglang.srt.managers.load_snapshot import (
     QueueMetrics,
     SpeculativeMetrics,
 )
-from sglang.srt.runtime_context import get_lora
+from sglang.srt.runtime_context import get_lora, get_parallel
 
 if TYPE_CHECKING:
     from sglang.srt.distributed.parallel_state_wrapper import ParallelState
@@ -215,7 +215,9 @@ class SchedulerLoadInquirer:
         decode_moments = list(totals) if totals[0] > 0 else None
 
         return LoadSnapshot(
-            dp_rank=int(self.ps.dp_rank) if self.ps.dp_rank is not None else 0,
+            dp_rank=int(get_parallel().dp_rank)
+            if get_parallel().dp_rank is not None
+            else 0,
             timestamp=time.time(),
             num_running_reqs=num_running_reqs,
             num_waiting_reqs=num_waiting_reqs,

python/sglang/srt/managers/scheduler_components/metrics_reporter.py

@@ -309,7 +309,7 @@ class SchedulerMetricsReporter:
         if (
             get_observability().enable_forward_pass_metrics
             and self.scheduler.ps.attn_tp_rank == 0
-            and self.scheduler.ps.pp_rank == self.scheduler.ps.pp_size - 1
+            and get_parallel().pp_rank == get_parallel().pp_size - 1
         ):
             from sglang.srt.observability.forward_pass_metrics import (
                 _FpmPublisherThread,

python/sglang/srt/managers/scheduler_components/output_streamer.py

@@ -32,7 +32,7 @@ from sglang.srt.managers.schedule_batch import (
     Req,
 )
 from sglang.srt.mem_cache.base_prefix_cache import BasePrefixCache
-from sglang.srt.runtime_context import get_observability, get_serving
+from sglang.srt.runtime_context import get_observability, get_parallel, get_serving
 from sglang.srt.server_args import ServerArgs
 from sglang.srt.speculative.spec_info import SpeculativeAlgorithm
 from sglang.srt.utils.weight_versions import compute_weight_version_spans
@@ -205,7 +205,7 @@ class SchedulerOutputStreamer:
 
         # Send to detokenizer
         payload = acc.to_payload(
-            dp_rank=self.ps.dp_rank,
+            dp_rank=get_parallel().dp_rank,
             is_idle_batch=is_idle_batch,
         )
         if payload is not None:
@@ -232,7 +232,7 @@ class SchedulerOutputStreamer:
     def _maybe_log_time_stats(self, *, req: Req) -> None:
         if (
             req.finished()
-            and self.ps.attn_tp_rank == 0
+            and get_parallel().attn_tp_rank == 0
             and get_observability().enable_request_time_stats_logging
         ):
             req.log_time_stats()

python/sglang/srt/managers/scheduler_components/profiler_manager.py

@@ -21,7 +21,7 @@ from sglang.srt.managers.io_struct import ProfileReq, ProfileReqOutput, ProfileR
 from sglang.srt.model_executor.forward_batch_info import ForwardMode
 from sglang.srt.model_executor.step_span_utils import set_detailed_annotations_enabled
 from sglang.srt.platforms import current_platform
-from sglang.srt.runtime_context import get_device
+from sglang.srt.runtime_context import get_device, get_parallel
 from sglang.srt.utils import is_mps, is_npu
 from sglang.srt.utils.profile_merger import ProfileMerger
 from sglang.srt.utils.profile_utils import ProfileManager
@@ -207,10 +207,13 @@ class SchedulerProfilerManager:
 
             self.rpd_profile_path = os.path.join(
                 self.torch_profiler_output_dir,
-                "rpd-" + str(time.time()) + f"-TP-{self.ps.tp_rank}" + ".trace.json.gz",
+                "rpd-"
+                + str(time.time())
+                + f"-TP-{get_parallel().tp_rank}"
+                + ".trace.json.gz",
             )
 
-            if self.ps.tp_rank == 0:
+            if get_parallel().tp_rank == 0:
                 import sqlite3
 
                 from rocpd.schema import RocpdSchema
@@ -282,13 +285,13 @@ class SchedulerProfilerManager:
         if not self.merge_profiles:
             return ""
 
-        if self.ps.tp_rank != 0:
+        if get_parallel().tp_rank != 0:
             return ""
-        if self.ps.dp_size > 1 and self.ps.dp_rank != 0:
+        if self.ps.dp_size > 1 and get_parallel().dp_rank != 0:
             return ""
-        if self.ps.pp_size > 1 and self.ps.pp_rank != 0:
+        if get_parallel().pp_size > 1 and get_parallel().pp_rank != 0:
             return ""
-        if self.ps.moe_ep_size > 1 and self.ps.moe_ep_rank != 0:
+        if get_parallel().moe_ep_size > 1 and get_parallel().moe_ep_rank != 0:
             return ""
 
         try:
@@ -336,15 +339,15 @@ class SchedulerProfilerManager:
             self.torch_profiler.stop()
             if not _is_npu:
                 # Build filename with only non-zero ranks to maintain backward compatibility
-                filename_parts = [self.profile_id, f"TP-{self.ps.tp_rank}"]
+                filename_parts = [self.profile_id, f"TP-{get_parallel().tp_rank}"]
 
                 # Only add other ranks if parallelism is enabled (size > 1)
                 if self.ps.dp_size > 1:
-                    filename_parts.append(f"DP-{self.ps.dp_rank}")
+                    filename_parts.append(f"DP-{get_parallel().dp_rank}")
-                if self.ps.pp_size > 1:
+                if get_parallel().pp_size > 1:
-                    filename_parts.append(f"PP-{self.ps.pp_rank}")
+                    filename_parts.append(f"PP-{get_parallel().pp_rank}")
-                if self.ps.moe_ep_size > 1:
+                if get_parallel().moe_ep_size > 1:
-                    filename_parts.append(f"EP-{self.ps.moe_ep_rank}")
+                    filename_parts.append(f"EP-{get_parallel().moe_ep_rank}")
 
                 filename = (
                     stage_prefix
@@ -364,7 +367,7 @@ class SchedulerProfilerManager:
             self.rpd_profiler.flush()
 
             torch.distributed.barrier(self.dp_tp_cpu_group)
-            if self.ps.tp_rank == 0:
+            if get_parallel().tp_rank == 0:
                 from sglang.srt.utils.rpd_utils import rpd_to_chrome_trace
 
                 rpd_to_chrome_trace("trace.rpd", self.rpd_profile_path)
@@ -376,7 +379,7 @@ class SchedulerProfilerManager:
                 self.torch_profiler_output_dir,
                 stage_prefix
                 + str(time.time())
-                + f"-TP-{self.ps.tp_rank}-memory"
+                + f"-TP-{get_parallel().tp_rank}-memory"
                 + stage_suffix
                 + ".pickle",
             )

python/sglang/srt/managers/scheduler_components/request_receiver.py

@@ -109,7 +109,7 @@ class SchedulerRequestReceiver:
 
         recv_reqs = self._broadcast_reqs_across_ranks(recv_reqs, local_reqs)
 
-        if self.ps.pp_rank == 0:
+        if get_parallel().pp_rank == 0:
             self.unwrap_pickle_wrapper(recv_reqs)
 
         recv_reqs = self._apply_mm_receiver(recv_reqs)
@@ -119,7 +119,7 @@ class SchedulerRequestReceiver:
         return recv_reqs
 
     def _pull_raw_reqs(self) -> Optional[List]:
-        if self.ps.pp_rank == 0:
+        if get_parallel().pp_rank == 0:
             if self.ps.attn_tp_rank == 0 and self.ps.attn_cp_rank == 0:
                 recv_reqs = []
 
@@ -158,10 +158,10 @@ class SchedulerRequestReceiver:
                 )
                 recv_reqs = point_to_point_pyobj(
                     [],
-                    self.ps.pp_rank * self.ps.tp_size + dp_offset,
+                    get_parallel().pp_rank * self.ps.tp_size + dp_offset,
                     self.world_group.cpu_group,
-                    (self.ps.pp_rank - 1) * self.ps.tp_size + dp_offset,
+                    (get_parallel().pp_rank - 1) * self.ps.tp_size + dp_offset,
-                    self.ps.pp_rank * self.ps.tp_size + dp_offset,
+                    get_parallel().pp_rank * self.ps.tp_size + dp_offset,
                 )
             else:
                 recv_reqs = None
@@ -232,7 +232,7 @@ class SchedulerRequestReceiver:
     def _apply_mm_receiver(self, recv_reqs: List) -> List:
         # Process MM requests under EPD-disaggregation mode
         if (
-            self.ps.pp_rank == 0
+            get_parallel().pp_rank == 0
             and get_disagg().language_only
             and get_disagg().encoder_transfer_backend
             in ["zmq_to_scheduler", "mooncake"]

python/sglang/srt/managers/scheduler_pp_mixin.py

@@ -103,7 +103,9 @@ class SchedulerPPMixin:
             for mb_id in range(self.pp_loop_size):
                 self.running_batch = self.running_mbs[mb_id]
                 self.last_batch = self.last_mbs[mb_id]
-                next_first_rank_mb_id = (mb_id + self.ps.pp_size) % self.pp_loop_size
+                next_first_rank_mb_id = (
+                    mb_id + get_parallel().pp_size
+                ) % self.pp_loop_size
                 next_mb_id = (mb_id + 1) % self.pp_loop_size
                 with torch.profiler.record_function("recv_requests"):
                     recv_reqs = self.ingest_requests()
@@ -243,7 +245,9 @@ class SchedulerPPMixin:
             for mb_id in range(self.pp_loop_size):
                 self.running_batch = self.running_mbs[mb_id]
                 self.last_batch = self.last_mbs[mb_id]
-                next_first_rank_mb_id = (mb_id + self.ps.pp_size) % self.pp_loop_size
+                next_first_rank_mb_id = (
+                    mb_id + get_parallel().pp_size
+                ) % self.pp_loop_size
                 next_mb_id = (mb_id + 1) % self.pp_loop_size
 
                 next_pp_outputs = None
@@ -391,7 +395,9 @@ class SchedulerPPMixin:
             for mb_id in range(self.pp_loop_size):
                 self.running_batch = self.running_mbs[mb_id]
                 self.last_batch = self.last_mbs[mb_id]
-                next_first_rank_mb_id = (mb_id + self.ps.pp_size) % self.pp_loop_size
+                next_first_rank_mb_id = (
+                    mb_id + get_parallel().pp_size
+                ) % self.pp_loop_size
                 next_mb_id = (mb_id + 1) % self.pp_loop_size
 
                 next_pp_outputs = None
@@ -561,7 +567,9 @@ class SchedulerPPMixin:
                     self.on_idle()
 
     def init_pp_loop_state(self: Scheduler):
-        self.pp_loop_size: int = self.ps.pp_size + get_parallel().pp_async_batch_depth
+        self.pp_loop_size: int = (
+            get_parallel().pp_size + get_parallel().pp_async_batch_depth
+        )
         self.mbs = [None] * self.pp_loop_size
         self.last_mbs = [None] * self.pp_loop_size
         self.running_mbs = [
@@ -573,7 +581,7 @@ class SchedulerPPMixin:
         self.last_rank_comm_queue: deque[Tuple[torch.Event, PPProxyTensors]] = deque()
         self._pp_spec_relay = (
             envs.SGLANG_ENABLE_PP_SPEC.get()
-            and self.ps.pp_size > 1
+            and get_parallel().pp_size > 1
             and not self.spec_algorithm.is_none()
         )
 
@@ -805,31 +813,39 @@ class SchedulerPPMixin:
 
     def _pp_send_pyobj_to_next_stage(self: Scheduler, data, async_send: bool = False):
         p2p_work = []
-        if self.ps.attn_tp_rank == 0 and self.ps.attn_cp_rank == 0:
+        if get_parallel().attn_tp_rank == 0 and get_parallel().attn_cp_rank == 0:
             dp_offset = (
-                self.ps.attn_dp_rank * self.ps.attn_cp_size * self.ps.attn_tp_size
+                self.ps.attn_dp_rank
+                * get_parallel().attn_cp_size
+                * get_parallel().attn_tp_size
             )
             p2p_work = point_to_point_pyobj(
                 data,
-                self.ps.pp_rank * self.ps.tp_size + dp_offset,
+                get_parallel().pp_rank * get_parallel().tp_size + dp_offset,
                 self.world_group.cpu_group,
-                self.ps.pp_rank * self.ps.tp_size + dp_offset,
+                get_parallel().pp_rank * get_parallel().tp_size + dp_offset,
-                ((self.ps.pp_rank + 1) % self.ps.pp_size) * self.ps.tp_size + dp_offset,
+                ((get_parallel().pp_rank + 1) % get_parallel().pp_size)
+                * get_parallel().tp_size
+                + dp_offset,
                 async_send=async_send,
             )
         return p2p_work
 
     def _pp_recv_pyobj_from_prev_stage(self: Scheduler):
-        if self.ps.attn_tp_rank == 0 and self.ps.attn_cp_rank == 0:
+        if get_parallel().attn_tp_rank == 0 and get_parallel().attn_cp_rank == 0:
             dp_offset = (
-                self.ps.attn_dp_rank * self.ps.attn_cp_size * self.ps.attn_tp_size
+                self.ps.attn_dp_rank
+                * get_parallel().attn_cp_size
+                * get_parallel().attn_tp_size
             )
             data = point_to_point_pyobj(
                 [],
-                self.ps.pp_rank * self.ps.tp_size + dp_offset,
+                get_parallel().pp_rank * get_parallel().tp_size + dp_offset,
                 self.world_group.cpu_group,
-                ((self.ps.pp_rank - 1) % self.ps.pp_size) * self.ps.tp_size + dp_offset,
+                ((get_parallel().pp_rank - 1) % get_parallel().pp_size)
-                self.ps.pp_rank * self.ps.tp_size + dp_offset,
+                * get_parallel().tp_size
+                + dp_offset,
+                get_parallel().pp_rank * get_parallel().tp_size + dp_offset,
             )
         else:
             data = None
@@ -1470,7 +1486,7 @@ class SchedulerPPMixin:
         # posted, so the parity-based send-first/recv-first ordering used
         # for NPU is replaced by batch_isend_irecv which submits all
         # send/recv operations atomically.
-        if _is_npu and self.ps.pp_size == 2:
+        if _is_npu and get_parallel().pp_size == 2:
             return self._pp2_only_send_recv_output_tensors_npu(
                 next_first_rank_mb_id,
                 next_mb_id,
@@ -1498,7 +1514,7 @@ class SchedulerPPMixin:
         # makes rank 1 post its recv first, which breaks the cycle for any
         # pp_size > 1.
         needs_pairing = is_xpu() or self._pp_spec_relay
-        send_first = (not needs_pairing) or ((self.ps.pp_rank % 2) == 0)
+        send_first = (not needs_pairing) or ((get_parallel().pp_rank % 2) == 0)
 
         def _do_send():
             return self._pp_send_output_to_next_stage(

python/sglang/srt/managers/tp_worker.py

@@ -418,7 +418,7 @@ class TpModelWorker(BaseTpWorker):
         else:
             self.random_seed = broadcast_pyobj(
                 [get_device().random_seed],
-                self.ps.tp_size * self.ps.pp_rank + self.ps.tp_rank,
+                self.ps.tp_size * get_parallel().pp_rank + self.ps.tp_rank,
                 self.world_group.cpu_group,
                 src=self.world_group.ranks[0],
             )[0]
@@ -451,7 +451,8 @@ class TpModelWorker(BaseTpWorker):
         assert self.model_runner.max_running_requests > 0, "max_running_request is zero"
         max_req_len = min(
             self.model_config.context_len - 1,
-            self.model_runner.effective_max_total_num_tokens * self.ps.attn_dcp_size
+            self.model_runner.effective_max_total_num_tokens
+            * get_parallel().attn_dcp_size
             - 1,
         )
         assert max_req_len > 0, "Memory pool size is too small"
@@ -578,7 +579,8 @@ class TpModelWorker(BaseTpWorker):
     def get_worker_info(self):
         max_req_len = min(
             self.model_config.context_len - 1,
-            self.model_runner.effective_max_total_num_tokens * self.ps.attn_dcp_size
+            self.model_runner.effective_max_total_num_tokens
+            * get_parallel().attn_dcp_size
             - 1,
         )
         return (

python/sglang/srt/mem_cache/kv_cache_configurator.py

@@ -2420,7 +2420,9 @@ class KVCacheConfigurator:
                 sum(1 for i in all_mamba_layers if start <= i < end)
                 for start, end in (
                     get_pp_indices(
-                        self.model_config.num_hidden_layers, rank, self.ps.pp_size
+                        self.model_config.num_hidden_layers,
+                        rank,
+                        self.ps.pp_size,
                     )
                     for rank in range(self.ps.pp_size)
                 )

python/sglang/srt/model_executor/model_runner.py

@@ -445,7 +445,7 @@ class ModelRunner:
         self.prefill_shared_read_stager: Optional[Callable[[ForwardBatch], bool]] = None
 
         # CPU offload
-        set_offloader(create_offloader(dp_rank=self.ps.dp_rank))
+        set_offloader(create_offloader(dp_rank=get_parallel().dp_rank))
 
         self._weight_checker = WeightChecker(get_model=lambda: self.model, ps=self.ps)
 
@@ -481,7 +481,7 @@ class ModelRunner:
             "pp_proxy_tensors" in inspect.signature(self.model.forward).parameters
         )
 
-        if self.ps.pp_size > 1:
+        if get_parallel().pp_size > 1:
             if not (envs.SGLANG_ENABLE_PP_SPEC.get() and self.is_draft_worker):
                 assert self.support_pp, (
                     "Pipeline Parallel is not compatible with this model."
@@ -647,8 +647,8 @@ class ModelRunner:
             from sglang.srt.model_executor.mindspore_runner import init_ms_distributed
 
             init_ms_distributed(
-                world_size=self.ps.tp_size * self.ps.pp_size,
+                world_size=self.ps.tp_size * get_parallel().pp_size,
-                rank=self.ps.tp_size * self.ps.pp_rank + self.ps.tp_rank,
+                rank=self.ps.tp_size * get_parallel().pp_rank + self.ps.tp_rank,
                 local_rank=self.gpu_id,
                 port=self.dist_port,
             )
@@ -667,8 +667,8 @@ class ModelRunner:
         prepare_moe_topk(
             model=self.model,
             model_config=self.model_config,
-            moe_ep_size=self.ps.moe_ep_size,
+            moe_ep_size=get_parallel().moe_ep_size,
-            moe_ep_rank=self.ps.moe_ep_rank,
+            moe_ep_rank=get_parallel().moe_ep_rank,
         )
 
         self.maybe_init_dwdp()
@@ -708,7 +708,7 @@ class ModelRunner:
     def maybe_init_expert_location_metadata(self):
         if self.is_draft_worker:
             return
-        expert_rank = self.ps.moe_ep_rank + (
+        expert_rank = get_parallel().moe_ep_rank + (
             get_parallel().ep_join_rank_offset
             if get_exec().moe.is_ep_scale_joiner
             else 0
@@ -767,8 +767,8 @@ class ModelRunner:
         self.expert_backup_client = (
             ExpertBackupClient(
                 model_config=self.model_config,
-                moe_ep_size=self.ps.moe_ep_size,
+                moe_ep_size=get_parallel().moe_ep_size,
-                moe_ep_rank=self.ps.moe_ep_rank,
+                moe_ep_rank=get_parallel().moe_ep_rank,
                 get_model=lambda: self.model,
             )
             if (
@@ -803,16 +803,16 @@ class ModelRunner:
     def get_pp_proxy_topk_size(self) -> Optional[int]:
         return misc_utils.resolve_pp_proxy_topk_size(
             model_config=self.model_config,
-            pp_size=self.ps.pp_size,
+            pp_size=get_parallel().pp_size,
-            pp_rank=self.ps.pp_rank,
+            pp_rank=get_parallel().pp_rank,
             start_layer=self.layer_info.start_layer,
         )
 
     def get_pp_proxy_residual_num_blocks(self) -> Optional[int]:
         return misc_utils.resolve_pp_proxy_residual_num_blocks(
             model_config=self.model_config,
-            pp_size=self.ps.pp_size,
+            pp_size=get_parallel().pp_size,
-            pp_rank=self.ps.pp_rank,
+            pp_rank=get_parallel().pp_rank,
             start_layer=self.layer_info.start_layer,
         )
 
@@ -980,7 +980,7 @@ class ModelRunner:
             swap_in_block_size=hisparse_cfg.swap_in_block_size,
             shared_index_layers=resolve_shared_index_layers(
                 hf_text_config=self.model_config.hf_text_config,
-                pp_size=self.ps.pp_size,
+                pp_size=get_parallel().pp_size,
                 is_speculative=self.spec_algorithm.is_speculative(),
             ),
         )
@@ -1157,8 +1157,8 @@ class ModelRunner:
         check_quantized_moe_compatibility(
             model_config=self.model_config,
             tp_size=self.ps.tp_size,
-            moe_ep_size=self.ps.moe_ep_size,
+            moe_ep_size=get_parallel().moe_ep_size,
-            moe_dp_size=self.ps.moe_dp_size,
+            moe_dp_size=get_parallel().moe_dp_size,
         )
 
     def init_torch_distributed(self):
@@ -1293,7 +1293,7 @@ class ModelRunner:
             is_draft_worker=self.is_draft_worker,
             tp_size=self.ps.tp_size,
             tp_rank=self.ps.tp_rank,
-            pp_rank=self.ps.pp_rank,
+            pp_rank=get_parallel().pp_rank,
         )
 
         if dumper.may_enable:
@@ -1580,7 +1580,7 @@ class ModelRunner:
         dp_size = 1 if get_parallel().enable_dp_attention else self.ps.dp_size
         self.local_omp_cpuid = numa_utils.init_threads_binding(
             numa_index=self.gpu_id,
-            world_size=dp_size * self.ps.tp_size * self.ps.pp_size,
+            world_size=dp_size * self.ps.tp_size * get_parallel().pp_size,
         )
 
     def apply_torch_tp(self):

python/sglang/srt/model_executor/runner/base_runner.py

@@ -274,7 +274,7 @@ class BaseRunner(ABC):
         if (
             envs.SGLANG_PP_PARALLEL_DEEPGEMM_WARMUP.get()
             and deep_gemm_wrapper.ENABLE_JIT_DEEPGEMM
-            and mr.ps.pp_size > 1
+            and get_parallel().pp_size > 1
             and not mr.spec_algorithm.is_speculative()
         ):
             from sglang.srt.layers.deep_gemm_wrapper.compile_utils import (
@@ -546,7 +546,7 @@ class BaseRunner(ABC):
             pp_hidden_tokens = num_tokens
             if (
                 capture_forward_mode == ForwardMode.EXTEND
-                and mr.ps.pp_rank != 0
+                and get_parallel().pp_rank != 0
                 and mr.ps.attn_cp_size > 1
             ):
                 pp_hidden_tokens = num_tokens // mr.ps.attn_cp_size

python/sglang/srt/model_executor/runner/flashinfer_autotune.py

@@ -30,6 +30,7 @@ from sglang.srt.runtime_context import (
     get_disagg,
     get_exec,
     get_model,
+    get_parallel,
     get_schedule,
     get_spec,
     max_prefill_buffer_tokens,
@@ -147,7 +148,7 @@ def flashinfer_autotune_cache_path(model_runner: ModelRunner) -> Path:
         str(get_model().quantization),
         str(get_exec().moe.moe_runner_backend),
         str(mr.ps.tp_size),
-        str(mr.ps.pp_size),
+        str(get_parallel().pp_size),
         str(mr.ps.attn_dp_size),
         str(mr.ps.moe_ep_size),
         str(mr.model_config.hf_config.__class__.__name__),
@@ -170,7 +171,7 @@ def flashinfer_autotune_cache_path(model_runner: ModelRunner) -> Path:
     cache_dir.mkdir(parents=True, exist_ok=True)
     return (
         cache_dir
-        / f"rank_tp{mr.ps.tp_rank}_pp{mr.ps.pp_rank}_dp{mr.ps.dp_rank or 0}.json"
+        / f"rank_tp{mr.ps.tp_rank}_pp{get_parallel().pp_rank}_dp{mr.ps.dp_rank or 0}.json"
     )
 
 

python/sglang/srt/observability/metrics_collector.py

@@ -34,6 +34,7 @@ from sglang.srt.runtime_context import (
     get_context,
     get_disagg,
     get_observability,
+    get_parallel,
     get_schedule,
     get_serving,
 )
@@ -1118,7 +1119,7 @@ class SchedulerMetricsCollector(_StatLoggerDIMixin):
         )
         enable_kv_cache_events = bool(
             get_observability().kv_events_config
-            and ps.pp_rank == 0
+            and get_parallel().pp_rank == 0
             and ps.attn_tp_rank == 0
             and ps.attn_cp_rank == 0
         )

python/sglang/srt/ray/scheduler_actor.py

@@ -21,7 +21,7 @@ from typing import Any, Dict, Optional
 import ray
 
 from sglang.srt.arg_groups.overrides import declare_resolution
-from sglang.srt.runtime_context import publish
+from sglang.srt.runtime_context import SpawnRanks, publish, spawn_world_rank
 from sglang.srt.server_args import PortArgs, ServerArgs
 
 logger = logging.getLogger(__name__)
@@ -49,7 +49,11 @@ class SchedulerActor:
         dist_init_addr: Optional[str] = None,
     ):
         from sglang.srt.environ import envs
-        from sglang.srt.managers.scheduler import Scheduler, configure_scheduler_process
+        from sglang.srt.managers.scheduler import (
+            Scheduler,
+            configure_scheduler_process,
+            resolve_spawn_dp_rank,
+        )
         from sglang.srt.utils.numa_utils import (
             get_numa_node_if_available,
             numa_bind_to_node,
@@ -77,12 +81,23 @@ class SchedulerActor:
             actual_gpu_id = gpu_id
             logger.info(f"[TP{tp_rank}] Using passed gpu_id: {gpu_id}")
 
+        dp_rank = resolve_spawn_dp_rank(dp_rank)
+
         # This actor takes the place of run_scheduler_process, which is where
         # a forked scheduler publishes.
-        publish(server_args, role="scheduler")
+        publish(
+            server_args,
+            role="scheduler",
+            ranks=SpawnRanks(
+                world_rank=spawn_world_rank(
+                    server_args, tp_rank=tp_rank, pp_rank=pp_rank
+                ),
+                dp_rank=dp_rank,
+            ),
+        )
 
         # Configure worker (logging, process title, etc.)
-        dp_rank = configure_scheduler_process(
+        configure_scheduler_process(
             server_args,
             actual_gpu_id,
             tp_rank,

python/sglang/srt/runtime_context.py

@@ -132,6 +132,10 @@ class Live(msgspec.Struct, frozen=True):
 
     source: Any = None
     doc: str = ""
+    # For a stamp-only name (`source=None`): what a reader should be told when
+    # nothing has stamped it. These names have no fallback by construction, so
+    # the message is the only thing pointing at what did not happen.
+    unstamped: str = ""
 
 
 _LIVE_READS: dict = {
@@ -177,7 +181,35 @@ _LIVE_READS: dict = {
     "attn_cp_rank": "get_attn_context_model_parallel_rank",
     "dcp_rank": "get_dcp_rank",
     "attn_dcp_rank": lambda self: self.dcp_rank if self.dcp_enabled else 0,
-    "attn_dp_rank": None,
+    "attn_dp_rank": Live(
+        source=None,
+        doc=(
+            "This process's index in the attention-DP group. Computed from "
+            "`tp_rank` when the attention topology is initialized, and moved "
+            "by an elastic scale-up, so no coordinator can answer it."
+        ),
+        unstamped=(
+            "it is computed from this process's `tp_rank` when the attention "
+            "topology is initialized, so a process that never ran "
+            "`initialize_dp_attention` has no answer to give"
+        ),
+    ),
+    "dp_rank": Live(
+        source=None,
+        doc=(
+            "Which data-parallel replica this process serves, as the data "
+            "parallel controller numbered them at spawn. `None` when there is "
+            "no controller. Unlike `attn_dp_rank` and `moe_dp_rank` it is not "
+            "a position in any process group -- no group has one member per "
+            "replica -- which is why nothing can derive it and the spawn "
+            "states it instead."
+        ),
+        unstamped=(
+            "it is a spawn identity, handed to `publish(..., ranks=...)` by "
+            "the process entry; a process that published without a rank "
+            "bundle has no replica index to report"
+        ),
+    ),
     "world_group": "get_world_group",
     "tp_group": "get_tp_group",
     "pp_group": "get_pp_group",
@@ -227,6 +259,80 @@ def derive_attention_widths(
     return attn_dp_size, tp_size // attn_dp_size // attn_cp_size
 
 
+def derive_attention_ranks(
+    *, tp_rank: int, attn_tp_size: int, attn_cp_size: int, enable_dp_attention: bool
+) -> tuple:
+    """(attn_tp_rank, attn_dp_rank) for a process at `tp_rank`.
+
+    The rank layout is (dp, cp, tp) with tp the fastest-changing dimension::
+
+        tp_rank = (attn_dp_rank * attn_cp_size + attn_cp_rank) * attn_tp_size
+                  + attn_tp_rank
+
+    Split out beside `derive_attention_widths` because two places need it from
+    different inputs: `publish` has this process's `tp_rank` from the spawn and
+    the widths from the configuration, while `initialize_dp_attention` has them
+    from the groups it just built. They must not carry separate copies of the
+    arithmetic -- the point of computing it at publish is that the two agree.
+    """
+    attn_tp_rank = tp_rank % attn_tp_size
+    if not enable_dp_attention:
+        return attn_tp_rank, 0
+    return attn_tp_rank, tp_rank // (attn_tp_size * attn_cp_size)
+
+
+def spawn_world_rank(server_args, *, tp_rank: int, pp_rank: int) -> int:
+    """This process's place in WORLD, from the ranks its entry was given.
+
+    The inverse of `derive_spawn_ranks`, for the entries that have the pieces
+    but not the whole: the same expression `bootstrap` hands to
+    `init_distributed_environment` when it builds the group.
+
+    Reads a resolving view because it runs before `publish`.
+    """
+    from sglang.srt.arg_groups.model_override_base import resolving_view
+
+    cfg = resolving_view(server_args)
+    return cfg.ep_join_rank_offset + cfg.tp_size * pp_rank + tp_rank
+
+
+def derive_spawn_ranks(
+    *,
+    world_rank: int,
+    tp_size: int,
+    ep_join_rank_offset: int,
+    attn_cp_size: int,
+    attn_tp_size: int,
+    moe_dp_size: int,
+    moe_ep_size: int,
+) -> dict:
+    """Every rank a process group would answer, from its place in WORLD.
+
+    WORLD is laid out `rank = ep_join_rank_offset + tp_size * pp_rank +
+    tp_rank`: `initialize_model_parallel` builds tensor-parallel groups as
+    contiguous blocks of `tp_size` and pipeline groups strided by it, so the
+    map is a bijection and this is its inverse. The attention and MoE ranks
+    are then positions inside the tensor-parallel block, which is what the
+    launcher computes when it decides what to spawn.
+
+    Pure arithmetic over the published widths: no group is consulted, which is
+    the point -- this runs at publish, before any of them exist.
+    """
+    local = world_rank - ep_join_rank_offset
+    tp_rank = local % tp_size
+    return {
+        "tp_rank": tp_rank,
+        "pp_rank": local // tp_size,
+        "attn_cp_rank": (tp_rank // attn_tp_size) % attn_cp_size,
+        "moe_dp_rank": tp_rank // (tp_size // moe_dp_size),
+        "moe_ep_rank": (
+            tp_rank
+            % (tp_size // moe_dp_size)
+            // (tp_size // moe_dp_size // moe_ep_size)
+        ),
+    }
+
+
 def derive_parallel_widths(
     *,
     tp_size: int,
@@ -327,6 +433,31 @@ def dcp_enabled_of(cfg: Any):
     return parallel_widths_of(cfg)["dcp_enabled"]
 
 
+class SpawnRanks(msgspec.Struct, frozen=True):
+    """Where the launcher put this process, in the two numbers only it knows.
+
+    `world_rank` is this process's place in the WORLD group, which fixes every
+    other rank: the groups are laid out from the published widths, so
+    `tp_rank`, `pp_rank` and the attention / MoE ranks are functions of it (see
+    `derive_spawn_ranks`). Passing them separately would be passing the same
+    fact five more times, with five more ways for an entry to contradict
+    itself.
+
+    `dp_rank` is the exception, because data-parallel replicas are separate
+    WORLD groups: with `--dp-size 2` each replica holds ranks `0 .. n-1`, so
+    the rank cannot say which replica this is. `None` means "no controller",
+    which is an answer rather than an absence, and it is recorded as one.
+
+    Nothing else belongs here. A device index, for instance, is a placement
+    decision rather than a position -- the launcher may reindex it, and Ray
+    assigns it from its own allocator -- so it stays an argument to whoever
+    was handed it.
+    """
+
+    world_rank: int
+    dp_rank: Optional[int] = None
+
+
 class ParallelContext:
     """Parallel-topology namespace: one spelling per name.
 
@@ -394,11 +525,10 @@ class ParallelContext:
                 return getattr(_ps(), source)()
             if source is not None:
                 return source(self)
+            why = live.unstamped if isinstance(live, Live) else ""
             raise RuntimeError(
-                f"parallel rank {name!r} is not available: it is computed from "
+                f"parallel name {name!r} is not available: "
-                "this process's `tp_rank` when the attention topology is "
+                + (why or "nothing has stamped it in this process")
-                "initialized, so a process that never ran "
-                "`initialize_dp_attention` has no answer to give"
             )
         if config is None and name in _parallel_config_leaves():
             raise ValueError("config namespace 'parallel' not published")
@@ -1598,7 +1728,13 @@ def _dump_recorded_namespace_reads() -> None:
         )
 
 
-def publish(server_args, *, role: str, hf_config: Any = None) -> RuntimeContext:
+def publish(
+    server_args,
+    *,
+    role: str,
+    hf_config: Any = None,
+    ranks: SpawnRanks | None = None,
+) -> RuntimeContext:
     """Install process-wide config for this OS process.
 
     Records the process ``role`` — one of the ``ROLE_NAMESPACE_SETS`` keys,
@@ -1609,6 +1745,12 @@ def publish(server_args, *, role: str, hf_config: Any = None) -> RuntimeContext:
     namespace-read enforcement (``record`` audits the reads instead).
     ``hf_config`` is accepted for forward-compat and currently unused.
 
+    ``ranks`` is who this process is, from the entry that spawned it. It is
+    optional because most roles are not placed in the topology at all -- a
+    tokenizer has no ``tp_rank`` -- and those processes raise on a rank read
+    exactly as they do today, with a message naming the missing bundle rather
+    than an absent process group.
+
     A process holds at most one live config: the bags always describe the
     engine running now. Re-publish is allowed and is **last-publish-wins**
     (bags re-projected, provenance reset, role overwritten), which is what
@@ -1634,6 +1776,36 @@ def publish(server_args, *, role: str, hf_config: Any = None) -> RuntimeContext:
             ),
         )
     _CONTEXT._publish_role = role
+    if ranks is not None:
+        # The placement, worked out here rather than carried: the widths are on
+        # the bag a moment ago, and `world_rank` fixes the rest. A read of any
+        # of these then needs no process group, which is the point -- they are
+        # read long before one exists. The scoped overrides that swap a group
+        # for a draft worker sit above the record in the read chain, so a
+        # scope still wins.
+        parallel = _CONTEXT.parallel
+        placement = derive_spawn_ranks(
+            world_rank=ranks.world_rank,
+            tp_size=parallel.tp_size,
+            ep_join_rank_offset=parallel.ep_join_rank_offset,
+            attn_cp_size=parallel.attn_cp_size,
+            attn_tp_size=parallel.attn_tp_size,
+            moe_dp_size=parallel.moe_dp_size,
+            moe_ep_size=parallel.moe_ep_size,
+        )
+        # `moe_dp_rank` is a different quantity when the MoE-DP group is
+        # aliased to the attention-CP one: the group answers the CP index,
+        # while this computes the MoE-DP index. Leave it to the group there, so
+        # one name does not mean two things.
+        if parallel.moe_dp_size < parallel.attn_cp_size:
+            placement.pop("moe_dp_rank")
+        # `dp_rank` is recorded whatever it is, None included: replicas are
+        # separate WORLD groups, so no rank implies it and `None` is the answer
+        # "no controller" rather than an absence.
+        placement["dp_rank"] = ranks.dp_rank
+        placement["launch_world_rank"] = ranks.world_rank
+        parallel.override_permanently(**placement)
+        _stamp_attention_ranks(parallel, placement["tp_rank"])
     if _ROLE_NS_MODE == "record":
         # The '-' marker distinguishes a zero-read role from a process where
         # recording never ran (signal teardown skips atexit).
@@ -1648,6 +1820,27 @@ def publish(server_args, *, role: str, hf_config: Any = None) -> RuntimeContext:
     return _CONTEXT
 
 
+def _stamp_attention_ranks(parallel, tp_rank: int) -> None:
+    """Place this process in the attention topology, from the configuration.
+
+    The widths are already on the bag -- `publish` computed them a moment ago --
+    and the rank comes from the spawn, so the position is known here, before any
+    process group exists. That is the point: a rank read then works in a process
+    that never initialises distributed, which is what `ParallelState` provided
+    by being a plain frozen record.
+
+    It is a stamp rather than a bag leaf because it is a per-process fact, and
+    nothing about the configuration distinguishes one rank from another.
+    """
+    attn_tp_rank, attn_dp_rank = derive_attention_ranks(
+        tp_rank=tp_rank,
+        attn_tp_size=parallel.attn_tp_size,
+        attn_cp_size=parallel.attn_cp_size,
+        enable_dp_attention=parallel.enable_dp_attention,
+    )
+    parallel.override_permanently(attn_tp_rank=attn_tp_rank, attn_dp_rank=attn_dp_rank)
+
+
 def assert_published(server_args, *, role: str) -> RuntimeContext:
     """This record, under this role, is already published -- or fail loud.
 

python/sglang/srt/rust_server/server.py

@@ -124,7 +124,7 @@ class RustServer:
             # The joining TP group is entirely local to this node.
             tp_size_per_node = scheduler.ps.tp_size
         else:
-            nnodes_per_pp_rank = max(get_parallel().nnodes // scheduler.ps.pp_size, 1)
+            nnodes_per_pp_rank = max(get_parallel().nnodes // get_parallel().pp_size, 1)
             tp_size_per_node = scheduler.ps.tp_size // nnodes_per_pp_rank
         dp_group_width = scheduler.ps.attn_tp_size * scheduler.ps.attn_cp_size
         # Count DP leaders within this node's TP range. The first leader must

python/sglang/srt/speculative/dflash_worker_v2.py

@@ -84,6 +84,7 @@ from sglang.srt.speculative.spec_utils import (
     GrammarTree,
     assign_req_to_token_pool_func,
     build_grammar_vocab_mask,
+    draft_pp_context,
     draft_tp_context,
 )
 from sglang.srt.utils import is_cuda, is_hip, is_npu, is_xpu
@@ -402,7 +403,7 @@ class DFlashWorkerV2(BaseSpecWorker):
             draft_init_ctx = draft_tp_context(get_parallel().attn_tp_group)
         else:
             draft_init_ctx = empty_context()
-        with draft_init_ctx:
+        with draft_pp_context(), draft_init_ctx:
             bundle = build_draft_tp_worker(
                 server_args=server_args,
                 gpu_id=gpu_id,
@@ -598,7 +599,10 @@ class DFlashWorkerV2(BaseSpecWorker):
         )
 
     def init_attention_backends(self):
-        with self.draft_tp_context(self.draft_model_runner.tp_group):
+        with (
+            draft_pp_context(),
+            self.draft_tp_context(self.draft_model_runner.tp_group),
+        ):
             self._draft_worker.init_attention_backends()
         self._need_mamba_verify_commit = mambaish_config(
             self.model_runner.model_config
@@ -608,7 +612,10 @@ class DFlashWorkerV2(BaseSpecWorker):
         )
 
     def init_cuda_graphs(self):
-        with self.draft_tp_context(self.draft_model_runner.tp_group):
+        with (
+            draft_pp_context(),
+            self.draft_tp_context(self.draft_model_runner.tp_group),
+        ):
             capture_decode_cuda_graph = (
                 get_exec().graph.cuda_graph_config.decode.backend != Backend.DISABLED
             )

python/sglang/srt/speculative/dspark_components/dspark_worker_v2.py

@@ -74,6 +74,7 @@ from sglang.srt.speculative.spec_tp_sync import SpecTpSync, SpecTpSyncSite
 from sglang.srt.speculative.spec_utils import (
     GrammarTree,
     build_grammar_vocab_mask,
+    draft_pp_context,
     draft_tp_context,
     prepare_mamba_track_for_verify,
 )
@@ -165,7 +166,7 @@ class DSparkWorkerV2(BaseSpecWorker):
                 "MoE-under-DP all-reduce."
             )
 
-        with self._draft_context():
+        with draft_pp_context(), self._draft_context():
             bundle = build_draft_tp_worker(
                 server_args=server_args,
                 gpu_id=gpu_id,
@@ -428,7 +429,7 @@ class DSparkWorkerV2(BaseSpecWorker):
         )
 
     def init_attention_backends(self):
-        with self._draft_context():
+        with draft_pp_context(), self._draft_context():
             self._draft_worker.init_attention_backends()
         self._target_hidden_projection_enabled = _configure_target_hidden_projection(
             target_model=self.target_worker.model_runner.model,
@@ -463,7 +464,7 @@ class DSparkWorkerV2(BaseSpecWorker):
                     "memory is available after target backend initialization.",
                     available_mem,
                 )
-        with self._draft_context():
+        with draft_pp_context(), self._draft_context():
             if capture_decode_cuda_graph:
                 # Keep the draft model graph enabled when folded proposal is
                 # disabled, but do not capture the proposal head as a tail

python/sglang/srt/speculative/eagle_worker_v2.py

@@ -338,6 +338,7 @@ class EagleDraftWorker(EagleDraftWorkerBase):
 
     def init_attention_backends(self):
         with (
+            draft_pp_context(),
             self.draft_tp_context(self.draft_runner.tp_group),
             speculative_moe_backend_context(),
             speculative_moe_a2a_backend_context(),
@@ -347,6 +348,7 @@ class EagleDraftWorker(EagleDraftWorkerBase):
 
     def init_cuda_graphs(self):
         with (
+            draft_pp_context(),
             self.draft_tp_context(self.draft_runner.tp_group),
             speculative_moe_backend_context(),
             speculative_moe_a2a_backend_context(),

python/sglang/srt/speculative/frozen_kv_mtp_worker_v2.py

@@ -73,6 +73,7 @@ from sglang.srt.speculative.frozen_kv_mtp_utils import (
 )
 from sglang.srt.speculative.spec_info import SpeculativeAlgorithm
 from sglang.srt.speculative.spec_utils import (
+    draft_pp_context,
     draft_tp_context,
     fast_topk,
     get_plan_stream,
@@ -134,7 +135,7 @@ class FrozenKVMTPDraftWorker(EagleDraftWorkerBase, TpModelWorker):
         self.hot_token_id = None
 
         with (
-            empty_context(),
+            draft_pp_context(),
             speculative_moe_backend_context(),
             speculative_moe_a2a_backend_context(),
             draft_model_build_scope(),
@@ -204,6 +205,7 @@ class FrozenKVMTPDraftWorker(EagleDraftWorkerBase, TpModelWorker):
 
     def init_attention_backends(self):
         with (
+            draft_pp_context(),
             self.draft_tp_context(self.draft_model_runner.tp_group),
             speculative_moe_backend_context(),
             speculative_moe_a2a_backend_context(),
@@ -214,6 +216,7 @@ class FrozenKVMTPDraftWorker(EagleDraftWorkerBase, TpModelWorker):
 
     def init_cuda_graphs(self):
         with (
+            draft_pp_context(),
             self.draft_tp_context(self.draft_model_runner.tp_group),
             speculative_moe_backend_context(),
             speculative_moe_a2a_backend_context(),

python/sglang/srt/speculative/multi_layer_eagle_worker_v2.py

@@ -82,6 +82,7 @@ from sglang.srt.speculative.multi_layer_eagle_utils import (
 )
 from sglang.srt.speculative.spec_info import SpeculativeAlgorithm
 from sglang.srt.speculative.spec_utils import (
+    draft_pp_context,
     draft_tp_context,
     get_plan_stream,
     sample_draft_proposal,
@@ -163,7 +164,7 @@ class MultiLayerEagleDraftWorker(EagleDraftWorkerBase):
 
         # Load draft model weights only.
         with (
-            empty_context(),
+            draft_pp_context(),
             speculative_moe_backend_context(),
             draft_model_build_scope(),
         ):
@@ -221,6 +222,7 @@ class MultiLayerEagleDraftWorker(EagleDraftWorkerBase):
 
     def init_attention_backends(self):
         with (
+            draft_pp_context(),
             self.draft_tp_context(self.draft_runner_list[0].tp_group),
             speculative_moe_backend_context(),
         ):
@@ -228,6 +230,7 @@ class MultiLayerEagleDraftWorker(EagleDraftWorkerBase):
 
     def init_cuda_graphs(self):
         with (
+            draft_pp_context(),
             self.draft_tp_context(self.draft_runner_list[0].tp_group),
             speculative_moe_backend_context(),
         ):

python/sglang/srt/speculative/standalone_worker_v2.py

@@ -27,7 +27,11 @@ from sglang.srt.speculative.base_spec_worker import (
 from sglang.srt.speculative.eagle_utils import default_tree_mask_mode
 from sglang.srt.speculative.eagle_worker_v2 import EagleDraftWorker, EAGLEWorkerV2
 from sglang.srt.speculative.spec_info import SpeculativeAlgorithm
-from sglang.srt.speculative.spec_utils import draft_tp_context, get_plan_stream
+from sglang.srt.speculative.spec_utils import (
+    draft_pp_context,
+    draft_tp_context,
+    get_plan_stream,
+)
 from sglang.srt.utils import empty_context, get_bool_env_var
 
 logger = logging.getLogger(__name__)
@@ -76,7 +80,7 @@ class StandaloneDraftWorker(EagleDraftWorker):
         # whose MoE gates run during construction; the scope routes their
         # fusion decision to the speculative leaf (it does not swap
         # runner_backend — the draft's forwards run outside that context).
-        with empty_context(), draft_model_build_scope():
+        with draft_pp_context(), draft_model_build_scope():
             self.draft_worker = TpModelWorker(
                 server_args=server_args,
                 gpu_id=gpu_id,

python/sglang/srt/utils/profile_utils.py

@@ -18,7 +18,7 @@ from sglang.srt.model_executor.step_span_utils import (
     set_detailed_annotations_enabled,
 )
 from sglang.srt.platforms import current_platform
-from sglang.srt.runtime_context import get_device
+from sglang.srt.runtime_context import get_device, get_parallel
 from sglang.srt.utils import is_npu
 from sglang.srt.utils.torch_npu_patch_utils import apply_torch_npu_patches
 
@@ -358,15 +358,15 @@ class _ProfilerTorch(_ProfilerConcreteBase):
         self.torch_profiler.stop()
         if not _is_npu:
             # Build filename with only non-zero ranks to maintain backward compatibility
-            filename_parts = [self.profile_id, f"TP-{self.ps.tp_rank}"]
+            filename_parts = [self.profile_id, f"TP-{get_parallel().tp_rank}"]
 
             # Only add other ranks if parallelism is enabled (size > 1)
             if self.ps.dp_size > 1:
-                filename_parts.append(f"DP-{self.ps.dp_rank}")
+                filename_parts.append(f"DP-{get_parallel().dp_rank}")
-            if self.ps.pp_size > 1:
+            if get_parallel().pp_size > 1:
-                filename_parts.append(f"PP-{self.ps.pp_rank}")
+                filename_parts.append(f"PP-{get_parallel().pp_rank}")
-            if self.ps.moe_ep_size > 1:
+            if get_parallel().moe_ep_size > 1:
-                filename_parts.append(f"EP-{self.ps.moe_ep_rank}")
+                filename_parts.append(f"EP-{get_parallel().moe_ep_rank}")
 
             filename = (
                 (self.output_prefix + "-" if self.output_prefix else "")
@@ -396,7 +396,7 @@ class _ProfilerMemory(_ProfilerConcreteBase):
             self.output_dir,
             (self.output_prefix + "-" if self.output_prefix else "")
             + str(time.time())
-            + f"-TP-{self.ps.tp_rank}-memory"
+            + f"-TP-{get_parallel().tp_rank}-memory"
             + self.output_suffix
             + ".pickle",
         )
@@ -426,10 +426,13 @@ class _ProfilerRPD(_ProfilerConcreteBase):
 
         self.rpd_profile_path = os.path.join(
             self.output_dir,
-            "rpd-" + str(time.time()) + f"-TP-{self.ps.tp_rank}" + ".trace.json.gz",
+            "rpd-"
+            + str(time.time())
+            + f"-TP-{get_parallel().tp_rank}"
+            + ".trace.json.gz",
         )
 
-        if self.ps.tp_rank == 0:
+        if get_parallel().tp_rank == 0:
             import sqlite3
 
             from rocpd.schema import RocpdSchema
@@ -454,7 +457,7 @@ class _ProfilerRPD(_ProfilerConcreteBase):
         self.rpd_profiler.flush()
 
         torch.distributed.barrier(self.cpu_group)
-        if self.ps.tp_rank == 0:
+        if get_parallel().tp_rank == 0:
             from sglang.srt.utils.rpd_utils import rpd_to_chrome_trace
 
             rpd_to_chrome_trace("trace.rpd", self.rpd_profile_path)

python/sglang/srt/weight_cache/daemon.py

@@ -51,9 +51,11 @@ from sglang.srt.arg_groups.overrides import resolving_view
 from sglang.srt.configs.load_config import LoadConfig
 from sglang.srt.platforms import current_platform
 from sglang.srt.runtime_context import (
+    SpawnRanks,
     get_exec,
     get_parallel,
     publish,
+    spawn_world_rank,
 )
 
 from .protocol import (
@@ -281,7 +283,17 @@ class WeightCacheDaemon:
         from sglang.srt.model_loader.loader import get_model_loader
 
         server_args = self.server_args
-        publish(server_args, role="weight_cache_daemon")
+        # The launcher told this daemon where it sits, and it builds the same
+        # groups a scheduler does, so the same one number places it.
+        publish(
+            server_args,
+            role="weight_cache_daemon",
+            ranks=SpawnRanks(
+                world_rank=spawn_world_rank(
+                    server_args, tp_rank=self.tp_rank, pp_rank=self.pp_rank
+                )
+            ),
+        )
 
         from sglang.srt.layers.moe import initialize_moe_config
 

python/sglang/test/test_utils.py

@@ -2,6 +2,7 @@
 
 import argparse
 import asyncio
+import contextlib
 import copy
 import doctest
 import importlib.util
@@ -2002,6 +2003,36 @@ def maybe_stub_sgl_kernel():
     sys.meta_path.insert(0, _SglKernelFinder())
 
 
+@contextlib.contextmanager
+def published_topology(role: str = "test", *, ranks=None, **server_args_fields):
+    """Publish a record describing the parallel topology a test wants.
+
+    Replaces standing a per-process parallel record into the object under
+    test. The widths arrive the way production gets them -- from published
+    configuration -- and the per-process ranks the way a spawned process gets
+    them, so a rank read is answered without building a process group. Stating
+    the topology through the same door production uses also keeps the derived
+    widths honest: a hand-built double can claim an `attn_tp_size` the
+    configuration would never produce.
+
+    `ranks` overrides the spawn identities; by default this process is rank
+    zero of the world, which fixes every other rank. The context is reset on exit, including when the
+    test fails.
+    """
+    from sglang.srt.runtime_context import SpawnRanks, publish, reset_context
+    from sglang.srt.server_args import ServerArgs
+
+    bundle = dict(world_rank=0, dp_rank=None)
+    bundle.update(ranks or {})
+    server_args = ServerArgs(model_path="dummy", **server_args_fields)
+    reset_context()
+    publish(server_args, role=role, ranks=SpawnRanks(**bundle))
+    try:
+        yield server_args
+    finally:
+        reset_context()
+
+
 _GPU_IDLE_TIMEOUT_SECS = 30.0
 _GPU_IDLE_POLL_INTERVAL_SECS = 2.0
 _GPU_IDLE_USED_MEMORY_THRESHOLD = 2 << 30  # 2 GiB
@@ -2253,6 +2284,17 @@ def enter_override(test_case, override):
     return installed
 
 
+def enter_scope(test_case, scope):
+    """Enter a context manager for the length of one test.
+
+    The `with`-statement form of `enter_override` above, and 3.10-safe for the
+    same reason: `enterContext` arrived in 3.11.
+    """
+    entered = scope.__enter__()
+    test_case.addCleanup(scope.__exit__, None, None, None)
+    return entered
+
+
 class CustomTestCase(unittest.TestCase):
     def __init_subclass__(cls, **kwargs):
         super().__init_subclass__(**kwargs)

test/registered/unit/constrained/test_grammar_manager.py

@@ -26,13 +26,19 @@ from sglang.srt.constrained.base_grammar_backend import (
 from sglang.srt.constrained.grammar_manager import GrammarManager
 from sglang.srt.constrained.reasoner_grammar_backend import ReasonerGrammarObject
 from sglang.srt.distributed.communication_tags import P2PTag
-from sglang.srt.runtime_context import get_context, publish, reset_context
+from sglang.srt.runtime_context import (
+    SpawnRanks,
+    get_context,
+    get_parallel,
+    publish,
+    reset_context,
+)
 from sglang.srt.sampling.sampling_params import (
     REQUEST_REASONING_END_TOKEN_IDS_KEY,
 )
 from sglang.srt.server_args import ServerArgs
 from sglang.test.ci.ci_register import register_cpu_ci
-from sglang.test.test_utils import enter_override
+from sglang.test.test_utils import enter_override, enter_scope
 
 register_cpu_ci(2.0, "base-a-test-cpu")
 
@@ -43,9 +49,10 @@ register_cpu_ci(est_time=5, suite="stage-b-test-cpu-intel")
 def _make_scheduler(grammar_backend_name="none", skip_tokenizer=False):
     """Create a mock scheduler with necessary attributes.
 
-    The grammar manager reads its config from the bags, so the settings that
+    The grammar manager reads its config and its place in the pipeline from
-    used to be hung off the mock are published instead. The caller resets the
+    the context, so the settings that used to be hung off the mock are
-    context; every test here goes through `_GrammarFixture`.
+    published instead. The caller resets the context; every test here goes
+    through `_GrammarFixture`.
     """
     reset_context()
     server_args = ServerArgs(
@@ -56,7 +63,11 @@ def _make_scheduler(grammar_backend_name="none", skip_tokenizer=False):
         constrained_json_whitespace_pattern=None,
         constrained_json_disable_any_whitespace=False,
     )
-    publish(server_args, role="scheduler")
+    publish(
+        server_args,
+        role="scheduler",
+        ranks=SpawnRanks(world_rank=0),
+    )
     scheduler = MagicMock()
     scheduler.server_args = server_args
     scheduler.model_config.request_selectable_think_end_id_sequences = None
@@ -66,8 +77,6 @@ def _make_scheduler(grammar_backend_name="none", skip_tokenizer=False):
     scheduler.dp_tp_group.world_size = 1
     scheduler.dp_tp_group.first_rank = 0
     scheduler.dp_tp_group.is_first_rank = True
-    scheduler.ps.pp_rank = 0
-    scheduler.ps.pp_size = 1
     scheduler.pp_group = None
 
     return scheduler
@@ -769,8 +778,10 @@ class TestGrammarManagerPPSync(unittest.TestCase):
         enter_override(
             self, get_context().override_server_args(skip_tokenizer_init=True)
         )
-        scheduler.ps.pp_rank = pp_rank
+        # After that override, not before: installing a server-args override
-        scheduler.ps.pp_size = pp_size
+        # re-resolves the parallel bag from defaults, which puts `pp_size`
+        # back to 1 whatever was published.
+        enter_scope(self, get_parallel().override(pp_size=pp_size, pp_rank=pp_rank))
         scheduler.pp_group = pp_group
         mgr = GrammarManager(scheduler)
         mgr.grammar_backend = MagicMock(spec=BaseGrammarBackend)

test/registered/unit/managers/test_auxiliary_output.py

@@ -27,6 +27,7 @@ from sglang.srt.runtime_context import publish, reset_context
 from sglang.srt.server_args import ServerArgs
 from sglang.srt.speculative.spec_info import SpeculativeAlgorithm
 from sglang.test.ci.ci_register import register_cpu_ci
+from sglang.test.test_utils import published_topology
 
 register_cpu_ci(est_time=14, suite="base-a-test-cpu")
 
@@ -453,7 +454,6 @@ def test_active_observer_uses_observer_logits_preprocessing():
 def test_scheduler_copies_auxiliary_output_for_non_overlap_results():
     event = object()
     scheduler = object.__new__(Scheduler)
-    scheduler.ps = SimpleNamespace(pp_size=1)
     scheduler.device_module = SimpleNamespace(Event=Mock(return_value=event))
     result = SimpleNamespace(
         logits_output=SimpleNamespace(auxiliary_device_output=object()),
@@ -463,6 +463,7 @@ def test_scheduler_copies_auxiliary_output_for_non_overlap_results():
     )
     batch = SimpleNamespace(return_logprob=False, return_hidden_states=False)
 
+    with published_topology():
         Scheduler._copy_auxiliary_output_to_cpu(scheduler, batch, result)
 
     assert result.copy_done is event
@@ -474,7 +475,6 @@ def test_scheduler_copies_auxiliary_output_for_non_overlap_results():
 
 def test_scheduler_preserves_pipeline_parallel_output_for_transport():
     scheduler = object.__new__(Scheduler)
-    scheduler.ps = SimpleNamespace(pp_size=2)
     scheduler.device_module = SimpleNamespace(Event=Mock())
     result = SimpleNamespace(
         logits_output=SimpleNamespace(auxiliary_device_output=object()),
@@ -484,6 +484,7 @@ def test_scheduler_preserves_pipeline_parallel_output_for_transport():
     )
     batch = SimpleNamespace(return_logprob=False, return_hidden_states=False)
 
+    with published_topology(pp_size=2):
         Scheduler._copy_auxiliary_output_to_cpu(scheduler, batch, result)
 
     assert result.copy_done is None
@@ -514,7 +515,6 @@ def test_pdmux_split_prefill_schedules_auxiliary_output_copy():
     scheduler.is_generation = True
     scheduler.enable_overlap = False
     scheduler.enable_pdmux = True
-    scheduler.ps = SimpleNamespace(pp_size=1)
     scheduler.tp_worker = SimpleNamespace(
         forward_batch_split_prefill=Mock(return_value=result)
     )
@@ -535,9 +535,12 @@ def test_pdmux_split_prefill_schedules_auxiliary_output_copy():
         return_hidden_states=False,
     )
 
-    with patch(
+    with (
+        published_topology(),
+        patch(
             "sglang.srt.managers.scheduler.resolve_forward_inputs"
-    ) as resolve_forward_inputs:
+        ) as resolve_forward_inputs,
+    ):
         output_result = Scheduler.run_batch(scheduler, batch)
 
     resolve_forward_inputs.assert_called_once_with(batch, scheduler.future_map)

test/registered/unit/managers/test_output_streamer_customized_info.py

@@ -14,6 +14,7 @@ from sglang.srt.utils.weight_versions import (
     record_weight_version_events,
 )
 from sglang.test.ci.ci_register import register_cpu_ci
+from sglang.test.test_utils import enter_scope, published_topology
 
 register_cpu_ci(est_time=10, suite="base-a-test-cpu")
 
@@ -102,6 +103,8 @@ class TestOutputStreamerCustomizedInfo(unittest.TestCase):
         )
         serving_patch.start()
         observability_patch.start()
+        # The streamer asks the context which rank it is streaming from.
+        enter_scope(self, published_topology(ranks={"dp_rank": 0}))
         self.addCleanup(serving_patch.stop)
         self.addCleanup(observability_patch.stop)
 

test/registered/unit/managers/test_pp_cp_rank_offsets.py

@@ -3,7 +3,11 @@ from types import SimpleNamespace
 from unittest.mock import patch
 
 from sglang.test.ci.ci_register import register_cpu_ci
-from sglang.test.test_utils import maybe_stub_sgl_kernel
+from sglang.test.test_utils import (
+    enter_scope,
+    maybe_stub_sgl_kernel,
+    published_topology,
+)
 
 maybe_stub_sgl_kernel()
 
@@ -32,6 +36,25 @@ def _make_ps(**overrides) -> ParallelState:
     return ParallelState.trivial(**defaults)
 
 
+def _published_topology():
+    """The topology `_make_ps` describes, published instead of stood in.
+
+    World rank 12 of a `tp=8, pp=2` world is `tp_rank=4` on the second stage,
+    which puts this process at `attn_dp_rank=1` with `attn_tp_rank=0`: the
+    context derives all of them from that one number and the widths, where the
+    record above had to be handed each.
+    """
+    return published_topology(
+        role="scheduler",
+        ranks={"world_rank": 12, "dp_rank": 1},
+        tp_size=8,
+        pp_size=2,
+        dp_size=2,
+        attn_cp_size=2,
+        enable_dp_attention=True,
+    )
+
+
 def _fake_group() -> SimpleNamespace:
     return SimpleNamespace(rank=0, ranks=[0], cpu_group=object())
 
@@ -158,6 +181,7 @@ class TestRequestReceiverBroadcast(unittest.TestCase):
 class TestPPCPRankOffsets(unittest.TestCase):
     def test_request_receiver_uses_cp_size_for_pp_recv_rank(self):
         ps = _make_ps()
+        enter_scope(self, _published_topology())
         calls = []
 
         def fake_point_to_point_pyobj(data, rank, group, src, dst, **kwargs):
@@ -176,6 +200,7 @@ class TestPPCPRankOffsets(unittest.TestCase):
 
     def test_pp_mixin_uses_cp_size_for_pyobj_send_and_recv_rank(self):
         ps = _make_ps()
+        enter_scope(self, _published_topology())
         scheduler = SchedulerPPMixin()
         scheduler.ps = ps
         scheduler.world_group = _fake_group()

test/registered/unit/managers/test_scheduler_chunked_abort_race.py

@@ -5,7 +5,12 @@ from types import SimpleNamespace
 from unittest.mock import Mock
 
 from sglang.test.ci.ci_register import register_cpu_ci
-from sglang.test.test_utils import CustomTestCase, maybe_stub_sgl_kernel
+from sglang.test.test_utils import (
+    CustomTestCase,
+    enter_scope,
+    maybe_stub_sgl_kernel,
+    published_topology,
+)
 
 maybe_stub_sgl_kernel()
 
@@ -38,13 +43,16 @@ def _make_scheduler(pending_req, *, chunked_req, running_reqs) -> Scheduler:
     sched.disaggregation_mode = None
     sched.enable_hicache_storage = False
     sched.mm_receiver = None
-    sched.ps = SimpleNamespace(pp_size=1)
     sched.running_batch = SimpleNamespace(reqs=running_reqs)
     sched.last_batch = None
     return sched
 
 
 class TestPendingChunkedAbortRace(CustomTestCase):
+    def setUp(self):
+        # The abort path asks the context for the pipeline width.
+        enter_scope(self, published_topology())
+
     def test_req_left_chunked_slot_is_aborted(self):
         req = _FakeReq("zombie_rid")
         sched = _make_scheduler(req, chunked_req=None, running_reqs=[req])

test/registered/unit/managers/test_scheduler_hicache_events.py

@@ -5,7 +5,11 @@ from types import SimpleNamespace
 from unittest.mock import Mock, call, patch
 
 from sglang.test.ci.ci_register import register_cpu_ci
-from sglang.test.test_utils import maybe_stub_sgl_kernel
+from sglang.test.test_utils import (
+    enter_scope,
+    maybe_stub_sgl_kernel,
+    published_topology,
+)
 
 maybe_stub_sgl_kernel()
 
@@ -114,7 +118,7 @@ class TestSchedulerHiCacheEvents(unittest.TestCase):
         s = self.scheduler
         s.init_pp_loop_state = Mock()
         s.pp_loop_size = 1
-        s.ps = SimpleNamespace(pp_size=2)
+        enter_scope(self, published_topology(pp_size=2))
         s.pp_group = SimpleNamespace(is_last_rank=True)
         s.running_mbs = [self.running_batch]
         s.last_mbs = [None]

test/registered/unit/managers/test_scheduler_timeouts.py

@@ -12,7 +12,12 @@ from unittest.mock import MagicMock, patch
 
 from sglang.srt.environ import envs
 from sglang.test.ci.ci_register import register_cpu_ci
-from sglang.test.test_utils import CustomTestCase, maybe_stub_sgl_kernel
+from sglang.test.test_utils import (
+    CustomTestCase,
+    enter_scope,
+    maybe_stub_sgl_kernel,
+    published_topology,
+)
 
 maybe_stub_sgl_kernel()
 
@@ -62,7 +67,6 @@ def _scheduler(waiting_queue, running_reqs=(), last_batch_reqs=()):
     s.enable_unified_cache_external_linker = False
     s.ipc_channels = SimpleNamespace(send_to_tokenizer=MagicMock())
     s.beam_coordinator = MagicMock()
-    s.ps = SimpleNamespace(pp_size=1)
     s.running_batch = _batch(list(running_reqs))
     s.last_batch = _batch(list(last_batch_reqs)) if last_batch_reqs else None
     return s
@@ -126,6 +130,10 @@ class TestWaitingTimeout(CustomTestCase):
 
 
 class TestRunningTimeout(CustomTestCase):
+    def setUp(self):
+        # The poll asks the context for the pipeline width.
+        enter_scope(self, published_topology())
+
     def test_emits_only_stale_unfinished_reqs_without_marking(self):
         now = time.perf_counter()
         stale = _req("stale", forward_entry=now - 10)

test/registered/unit/model_executor/model_runner_components/test_startup_weight_load.py

@@ -736,12 +736,15 @@ class TestStartupWeightLoadSchedulerRouting(CustomTestCase):
         # publishing a record rather than by standing one in.
         reset_context()
         publish(
-            ServerArgs(model_path="dummy", startup_weight_load_mode=mode),
+            ServerArgs(
+                model_path="dummy",
+                startup_weight_load_mode=mode,
+                pp_size=pp_size,
+            ),
             role="scheduler",
         )
         scheduler = Scheduler.__new__(Scheduler)
         scheduler.enable_overlap = enable_overlap
-        scheduler.ps = SimpleNamespace(pp_size=pp_size)
         scheduler.init_tp_model_worker = lambda: setattr(scheduler, "tp_worker", worker)
         scheduler.maybe_init_draft_worker = lambda: setattr(
             scheduler, "draft_worker", draft_worker

test/registered/unit/multimodal/rust/shared/test_rust_server_extension.py

@@ -34,7 +34,6 @@ class TestRustServerExtension(CustomTestCase):
                 attn_dp_rank=1,
                 tp_size=2,
                 tp_rank=1,
-                pp_size=1,
                 attn_tp_size=1,
                 attn_cp_size=1,
             ),
@@ -49,7 +48,9 @@ class TestRustServerExtension(CustomTestCase):
                 ),
             ),
             patch.object(
-                server_module, "get_parallel", return_value=SimpleNamespace(nnodes=1)
+                server_module,
+                "get_parallel",
+                return_value=SimpleNamespace(nnodes=1, pp_size=1),
             ),
             patch.object(ModelServer, "_partition_cores", return_value=(None, None)),
             patch.object(

test/registered/unit/observability/test_forward_pass_metrics.py

@@ -1,4 +1,4 @@
-from sglang.srt.runtime_context import get_context, get_observability
+from sglang.srt.runtime_context import get_context, get_observability, get_parallel
 from sglang.test.ci.ci_register import register_cpu_ci
 
 register_cpu_ci(est_time=11, suite="base-a-test-cpu")
@@ -15,7 +15,7 @@ from sglang.srt.managers.scheduler_components.metrics_reporter import (
     SchedulerMetricsReporter,
     _CacheHitRateWindow,
 )
-from sglang.test.test_utils import CustomTestCase
+from sglang.test.test_utils import CustomTestCase, enter_scope
 
 
 def _make_ps(**overrides) -> ParallelState:
@@ -292,6 +292,8 @@ class TestForwardPassMetrics(unittest.TestCase):
             kv_events_config=None,
         )
         scheduler.ps = _make_ps(attn_tp_rank=0, dp_rank=2, pp_rank=0, pp_size=1)
+        # The reporter asks the context whether this is the last stage.
+        enter_scope(self, get_parallel().override(pp_rank=0, pp_size=1))
         scheduler.enable_kv_cache_events = False
 
         with patch(
@@ -329,6 +331,8 @@ class TestForwardPassMetrics(unittest.TestCase):
             kv_events_config=None,
         )
         scheduler.ps = _make_ps(attn_tp_rank=0, dp_rank=0, pp_rank=0, pp_size=2)
+        # The reporter asks the context whether this is the last stage.
+        enter_scope(self, get_parallel().override(pp_rank=0, pp_size=2))
         scheduler.enable_kv_cache_events = False
 
         with patch(

test/registered/unit/test_runtime_context.py

@@ -39,6 +39,7 @@ from sglang.srt.runtime_context import (
     Flags,
     ParallelContext,
     RuntimeContext,
+    SpawnRanks,
     _FlagGroupBase,
     assert_published,
     derive_parallel_widths,
@@ -200,6 +201,148 @@ class TestTheTwoWorldWidths(_IsolatedOverrides):
                 self.assertEqual(parallel.launch_world_size, 2)
 
 
+class TestSpawnIdentities(_IsolatedOverrides):
+    """`dp_rank` and `gpu_id` come from the spawn, because nothing else has them.
+
+    Both vary per process while the record is identical across them, and
+    neither is a position in any process group -- no group has one member per
+    data-parallel replica. So the process entry states them at publish.
+    """
+
+    def setUp(self):
+        super().setUp()
+        parallel = get_parallel()
+        self._saved_stamp = dict(parallel._stamp)
+        self.addCleanup(
+            lambda: (
+                parallel.clear_stamp(),
+                parallel.override_permanently(**self._saved_stamp),
+            )
+        )
+        reset_context()
+        self.addCleanup(reset_context)
+
+    def test_one_rank_fixes_the_rest(self):
+        """Every other rank is a position in a group laid out from the widths,
+        so `world_rank` is the whole placement: rank 5 of a `tp=4, pp=2` world
+        is the second stage's second device."""
+        publish(
+            ServerArgs(model_path="dummy", tp_size=4, pp_size=2),
+            role="test",
+            ranks=SpawnRanks(world_rank=5, dp_rank=2),
+        )
+        parallel = get_parallel()
+        self.assertEqual(parallel.launch_world_rank, 5)
+        self.assertEqual(parallel.tp_rank, 1)
+        self.assertEqual(parallel.pp_rank, 1)
+        self.assertEqual(parallel.dp_rank, 2)
+
+    def test_no_controller_is_an_answer_not_a_failure(self):
+        """`dp_rank=None` means "not under a data parallel controller", which
+        is a fact about the deployment, unlike never having been told. The
+        replicas are separate WORLD groups, so no rank implies it."""
+        publish(
+            ServerArgs(model_path="dummy", tp_size=2),
+            role="test",
+            ranks=SpawnRanks(world_rank=0, dp_rank=None),
+        )
+        self.assertIsNone(get_parallel().dp_rank)
+
+    def test_publishing_without_a_bundle_names_what_is_missing(self):
+        publish(ServerArgs(model_path="dummy", tp_size=2), role="test")
+        with self.assertRaises(RuntimeError) as caught:
+            get_parallel().dp_rank
+        self.assertIn("rank bundle", str(caught.exception))
+
+    def test_the_attention_rank_keeps_its_own_explanation(self):
+        """Two stamp-only names, two different reasons to be missing."""
+        publish(ServerArgs(model_path="dummy", tp_size=2), role="test")
+        with self.assertRaises(RuntimeError) as caught:
+            get_parallel().attn_dp_rank
+        self.assertIn("initialize_dp_attention", str(caught.exception))
+
+
+class TestAttentionRanksComeFromPublish(_IsolatedOverrides):
+    """With a spawn bundle, a rank read works before any group exists.
+
+    This is what `ParallelState` provided by being a plain frozen record, and
+    what the topology init could not: it needs the groups. Deriving at publish
+    is what lets a reader ask the context in a process that never initialises
+    distributed -- every unit test that builds a scheduler component, for one.
+    """
+
+    def setUp(self):
+        super().setUp()
+        parallel = get_parallel()
+        self._saved_stamp = dict(parallel._stamp)
+        self.addCleanup(
+            lambda: (
+                parallel.clear_stamp(),
+                parallel.override_permanently(**self._saved_stamp),
+            )
+        )
+        reset_context()
+        self.addCleanup(reset_context)
+
+    def test_it_matches_the_topology_init_for_every_shape(self):
+        """Cross-checked against the function the groups use, not restated.
+
+        Same inputs, two callers: one has them from the configuration and the
+        spawn, the other from the groups it just built.
+        """
+        from sglang.srt.layers.dp_attention import compute_dp_attention_world_info
+
+        shapes = [
+            (8, 1, 1, False),
+            (8, 2, 1, True),
+            (8, 4, 1, True),
+            (8, 2, 2, True),
+            (16, 4, 2, True),
+        ]
+        for tp_size, dp_size, attn_cp_size, dp_attn in shapes:
+            for tp_rank in range(tp_size):
+                reset_context()
+                publish(
+                    ServerArgs(
+                        model_path="dummy",
+                        tp_size=tp_size,
+                        dp_size=dp_size,
+                        attn_cp_size=attn_cp_size,
+                        enable_dp_attention=dp_attn,
+                    ),
+                    role="test",
+                    ranks=SpawnRanks(world_rank=tp_rank),
+                )
+                want_tp, _, want_dp, _ = compute_dp_attention_world_info(
+                    dp_attn, tp_rank, tp_size, dp_size, attn_cp_size
+                )
+                msg = f"tp={tp_size} dp={dp_size} cp={attn_cp_size} rank={tp_rank}"
+                self.assertEqual(get_parallel().attn_tp_rank, want_tp, msg)
+                self.assertEqual(get_parallel().attn_dp_rank, want_dp, msg)
+
+    def test_the_rank_reads_without_a_process_group(self):
+        """No distributed init, no patching of any getter."""
+        publish(
+            ServerArgs(
+                model_path="dummy", tp_size=8, dp_size=2, enable_dp_attention=True
+            ),
+            role="test",
+            ranks=SpawnRanks(world_rank=5),
+        )
+        with patch(
+            f"{_PS}.get_attn_tensor_model_parallel_rank",
+            side_effect=AssertionError("no group must be consulted"),
+        ):
+            self.assertEqual(get_parallel().attn_tp_rank, 1)
+            self.assertEqual(get_parallel().attn_dp_rank, 1)
+
+    def test_without_a_bundle_it_still_asks_the_group(self):
+        """Unchanged for every process that publishes without a placement."""
+        publish(ServerArgs(model_path="dummy", tp_size=8), role="test")
+        with patch(f"{_PS}.get_attn_tensor_model_parallel_rank", return_value=3):
+            self.assertEqual(get_parallel().attn_tp_rank, 3)
+
+
 class TestStampedRanks(_IsolatedOverrides):
     """`attn_dp_rank` comes from the stamp, and says so when there is none.
 
@@ -2107,5 +2250,108 @@ class TestTheDerivedHalfIsDeclared(CustomTestCase):
                 self.assertNotIn(name, fields)
 
 
+class TestAnEntryThatBuildsARunnerHandsOverItsPlacement(CustomTestCase):
+    """`ModelRunner.__init__` reads a recorded identity, so an entry that
+    publishes without a bundle and then builds one fails at construction.
+
+    Every such entry is an `__main__`-reachable path, so nothing in the unit
+    suite exercises it; the benchmark entry was found this way rather than by
+    a test. This walks the sources instead: a module that publishes and builds
+    a runner has to pass `ranks=`.
+    """
+
+    def test_every_publisher_that_builds_a_runner_passes_a_bundle(self):
+        import ast as _ast
+
+        root = _pathlib.Path(next(iter(_sglang.__path__))).resolve()
+        offenders = []
+        for path in root.rglob("*.py"):
+            text = path.read_text(encoding="utf-8-sig")
+            if "ModelRunner(" not in text or "publish(" not in text:
+                continue
+            tree = _ast.parse(text)
+            builds = any(
+                isinstance(n, _ast.Call)
+                and getattr(n.func, "id", getattr(n.func, "attr", None))
+                == "ModelRunner"
+                for n in _ast.walk(tree)
+            )
+            if not builds:
+                continue
+            for node in _ast.walk(tree):
+                if (
+                    isinstance(node, _ast.Call)
+                    and getattr(node.func, "id", None) == "publish"
+                    and not any(kw.arg == "ranks" for kw in node.keywords)
+                ):
+                    offenders.append(f"{path.relative_to(root)}:{node.lineno}")
+        self.assertEqual(
+            offenders,
+            [],
+            "these publish without a spawn bundle and then build a ModelRunner, "
+            "whose construction reads a recorded identity:\n  "
+            + "\n  ".join(offenders),
+        )
+
+
+class TestWhoAnswersDuringADraftScope(CustomTestCase):
+    """A draft worker runs in one process with the target, under a scope.
+
+    Two things have to hold for that to be workable, and neither is visible
+    from a single read: inside the scope every source agrees on the draft's
+    shape, and a reader that runs *outside* it still gets the draft's answer
+    from whatever it carried out.
+    """
+
+    def _single_member_group(self):
+        from sglang.srt.distributed.parallel_state import GroupCoordinator
+
+        group = GroupCoordinator.__new__(GroupCoordinator)
+        group.world_size = 1
+        group.rank_in_group = 0
+        return group
+
+    def _two_stage_pipeline(self):
+        """This process is stage 1 of 2, published the way a spawn states it."""
+        reset_context()
+        self.addCleanup(reset_context)
+        publish(
+            ServerArgs(model_path="dummy", pp_size=2),
+            role="scheduler",
+            ranks=SpawnRanks(world_rank=1),
+        )
+
+    def test_the_pipeline_swap_states_every_member_it_installs(self):
+        """`pp_size` is a configured leaf: unlike `pp_rank` it does not follow
+        the group being swapped underneath, so a scope that installs a group
+        without stating its width reports the target's."""
+        from sglang.srt.distributed import parallel_state
+
+        group = self._single_member_group()
+        self._two_stage_pipeline()
+        self.assertEqual(get_parallel().pp_size, 2)
+        with patch.object(parallel_state, "_PP", group):
+            with parallel_state.patch_pipeline_parallel_group(group):
+                self.assertEqual(get_parallel().pp_size, 1)
+                self.assertEqual(get_parallel().pp_rank, 0)
+                self.assertIs(get_parallel().pp_group, group)
+        self.assertEqual(get_parallel().pp_size, 2)
+        self.assertEqual(get_parallel().pp_rank, 1)
+
+    def test_a_report_built_for_a_runner_follows_that_runner(self):
+        """A weight check is an on-demand request served from the scheduler
+        loop, so it runs outside the scope that describes a draft runner. Its
+        report has to name the runner it was built for, which is why it holds
+        a record instead of asking the context."""
+        from sglang.srt.distributed.parallel_state_wrapper import ParallelState
+        from sglang.srt.utils.weight_checker import WeightChecker
+
+        draft = ParallelState.trivial(pp_rank=0, pp_size=1)
+        checker = WeightChecker(get_model=lambda: None, ps=draft)
+        self._two_stage_pipeline()
+        info = checker._parallelism_info()
+        self.assertEqual((info.pp_rank, info.pp_size), (0, 1))
+
+
 if __name__ == "__main__":
     unittest.main()

test/registered/unit/utils/test_weight_versions.py

@@ -15,7 +15,11 @@ from sglang.srt.utils.weight_versions import (
     truncate_weight_version_events,
 )
 from sglang.test.ci.ci_register import register_cpu_ci
-from sglang.test.test_utils import CustomTestCase
+from sglang.test.test_utils import (
+    CustomTestCase,
+    enter_scope,
+    published_topology,
+)
 
 register_cpu_ci(est_time=12, suite="base-a-test-cpu")
 
@@ -300,11 +304,9 @@ class _SchedulerStub:
         waiting,
         chunked=None,
         last_batch=None,
-        pp_size=1,
         hisparse=None,
     ):
         self.serving = _ServingStub(version)
-        self.ps = SimpleNamespace(pp_size=pp_size)
         self.running_batch = SimpleNamespace(reqs=running)
         self.last_batch = last_batch
         self.waiting_queue = waiting
@@ -313,7 +315,9 @@ class _SchedulerStub:
 
 
 class TestSchedulerRecordWeightVersionChange(CustomTestCase):
-    def _scheduler(self, *args, **kwargs):
+    def _scheduler(self, *args, pp_size=1, **kwargs):
+        # The recording path asks the context for the pipeline width.
+        enter_scope(self, published_topology(pp_size=pp_size))
         scheduler = _SchedulerStub(*args, **kwargs)
         for name, value in (
             ("get_serving", scheduler.serving),