From a84a98b1072008ebd36247295d0e2c8f1d30bed1 Mon Sep 17 00:00:00 2001
From: chenjian <1435317881@qq.com>
Date: Sun, 10 Aug 2025 13:54:59 +0800
Subject: [PATCH] fix scheduler bug due to async running (#3293)

---
 .../engine/sched/resource_manager_v1.py       | 27 ++++++++++++++-----
 fastdeploy/output/token_processor.py          |  7 +++++
 2 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/fastdeploy/engine/sched/resource_manager_v1.py b/fastdeploy/engine/sched/resource_manager_v1.py
index 73a180f77..61b34c468 100644
--- a/fastdeploy/engine/sched/resource_manager_v1.py
+++ b/fastdeploy/engine/sched/resource_manager_v1.py
@@ -56,6 +56,7 @@ class ResourceManagerV1(ResourceManager):
         self.running: list[Request] = []
         self.finish_execution_pool = ThreadPoolExecutor(max_workers=1)
         self.lock = threading.Lock()
+        self.to_be_rescheduled_request_id_set = set()
 
     def allocated_slots(self, request: Request):
         return len(request.block_tables) * self.config.cache_config.block_size
@@ -76,6 +77,13 @@ class ResourceManagerV1(ResourceManager):
 
     def _prepare_preempt_task(self, request):
         return ScheduledPreemptTask(idx=request.idx, request_id=request.request_id)
+    
+    def reschedule_preempt_task(self, request_id):
+        with self.lock:
+            if request_id in self.to_be_rescheduled_request_id_set and request_id in self.requests:
+                request = self.requests[request_id]
+                self.waiting.appendleft(request)
+                self.to_be_rescheduled_request_id_set.remove(request_id) 
 
     def _trigger_preempt(self, request, num_new_blocks, preempted_reqs, scheduled_reqs):
         can_schedule = True
@@ -85,7 +93,7 @@ class ResourceManagerV1(ResourceManager):
                 preempted_req.status = RequestStatus.PREEMPTED
                 preempted_req.num_computed_tokens = 0
                 self._free_blocks(preempted_req)
-                self.waiting.appendleft(preempted_req)
+                self.to_be_rescheduled_request_id_set.add(preempted_req.request_id)
                 preempted_reqs.append(preempted_req)
                 scheduled_reqs.append(self._prepare_preempt_task(preempted_req))
                 if preempted_req == request:
@@ -308,8 +316,9 @@ class ResourceManagerV1(ResourceManager):
         return self.real_bsz
 
     def add_request(self, request: Request) -> None:
-        self.waiting.append(request)
-        self.requests[request.request_id] = request
+        with self.lock:
+            self.waiting.append(request)
+            self.requests[request.request_id] = request
 
     def _free_blocks(self, request: Request):
         self.cache_manager.recycle_gpu_blocks(request.block_tables)
@@ -331,9 +340,15 @@ class ResourceManagerV1(ResourceManager):
                     if request is None:
                         # Invalid request ID.
                         continue
-                    request.status = RequestStatus.FINISHED
-                    self.running.remove(request)
-                    self._free_blocks(request)
+                    if request in self.running:  # normally run and finished
+                        self.running.remove(request)
+                        request.status = RequestStatus.FINISHED
+                        self._free_blocks(request)
+                    if request.request_id in self.to_be_rescheduled_request_id_set: # finished after preempted, blocks have been recycled.
+                        self.to_be_rescheduled_request_id_set.remove(request.request_id) # just remove from to_be_rescheduled_request_id_set
+                    if request in self.waiting:  # after finished, this request still scheduled from preempted to waiting, unexpected error, should not be here
+                        raise RuntimeError(f"request {request.request_id} scheduled into waiting list, after finished")
+
                     self.tasks_list[request.idx] = None
                     self.stop_flags[request.idx] = True
                     del self.requests[req_id]
diff --git a/fastdeploy/output/token_processor.py b/fastdeploy/output/token_processor.py
index 1f46a0952..bb94c04c4 100644
--- a/fastdeploy/output/token_processor.py
+++ b/fastdeploy/output/token_processor.py
@@ -432,6 +432,11 @@ class TokenProcessor:
             tokens = tokens[2 : batch + 2]
 
         batch_result = list()
+        if envs.ENABLE_V1_KVCACHE_SCHEDULER:
+            need_to_be_reschedule_req_ids = list(self.resource_manager.to_be_rescheduled_request_id_set)
+            for request_id in need_to_be_reschedule_req_ids:
+                if self.resource_manager.requests[request_id].idx >= (batch - 1):  # No more token generated for preempted request
+                    self.resource_manager.reschedule_preempt_task(request_id)
         for i in range(batch):
             if self.resource_manager.stop_flags[i]:
                 continue
@@ -458,6 +463,8 @@ class TokenProcessor:
                 if recovery_stop:
                     llm_logger.info(f"recovery stop signal found at task {task_id}")
                 if not recovery_stop and token_id < 0:
+                    if task_id in self.resource_manager.to_be_rescheduled_request_id_set:
+                        self.resource_manager.reschedule_preempt_task(task_id)
                     continue
 
             if task.get("prefill_chunk_info", None) is not None: