Support dynamic LoRA loading / unloading in engine/server API (#7446)

python/sglang/srt/entrypoints/EngineBase.py

@@ -48,6 +48,14 @@ class EngineBase(ABC):
         """Update model weights with in-memory tensor data."""
         pass
 
+    def load_lora_adapter(self, lora_name: str, lora_path: str):
+        """Load a new LoRA adapter without re-launching the engine."""
+        pass
+
+    def unload_lora_adapter(self, lora_name: str):
+        """Unload a LoRA adapter without re-launching the engine."""
+        pass
+
     @abstractmethod
     def release_memory_occupation(self):
         """Release GPU memory occupation temporarily."""

python/sglang/srt/entrypoints/engine.py

@@ -48,10 +48,12 @@ from sglang.srt.managers.io_struct import (
     GetWeightsByNameReqInput,
     ImageDataItem,
     InitWeightsUpdateGroupReqInput,
+    LoadLoRAAdapterReqInput,
     ReleaseMemoryOccupationReqInput,
     ResumeMemoryOccupationReqInput,
     RpcReqInput,
     RpcReqOutput,
+    UnloadLoRAAdapterReqInput,
     UpdateWeightFromDiskReqInput,
     UpdateWeightsFromDistributedReqInput,
     UpdateWeightsFromTensorReqInput,
@@ -478,6 +480,29 @@ class Engine(EngineBase):
             self.tokenizer_manager.get_weights_by_name(obj, None)
         )
 
+    def load_lora_adapter(self, lora_name: str, lora_path: str):
+        """Load a new LoRA adapter without re-launching the engine."""
+
+        obj = LoadLoRAAdapterReqInput(
+            lora_name=lora_name,
+            lora_path=lora_path,
+        )
+
+        loop = asyncio.get_event_loop()
+        return loop.run_until_complete(
+            self.tokenizer_manager.load_lora_adapter(obj, None)
+        )
+
+    def unload_lora_adapter(self, lora_name: str):
+        """Unload a LoRA adapter without re-launching the engine."""
+
+        obj = UnloadLoRAAdapterReqInput(lora_name=lora_name)
+
+        loop = asyncio.get_event_loop()
+        return loop.run_until_complete(
+            self.tokenizer_manager.unload_lora_adapter(obj, None)
+        )
+
     def release_memory_occupation(self, tags: Optional[List[str]] = None):
         obj = ReleaseMemoryOccupationReqInput(tags=tags)
         loop = asyncio.get_event_loop()

python/sglang/srt/entrypoints/http_server.py

@@ -72,6 +72,7 @@ from sglang.srt.managers.io_struct import (
     GenerateReqInput,
     GetWeightsByNameReqInput,
     InitWeightsUpdateGroupReqInput,
+    LoadLoRAAdapterReqInput,
     OpenSessionReqInput,
     ParseFunctionCallReq,
     ProfileReqInput,
@@ -80,6 +81,7 @@ from sglang.srt.managers.io_struct import (
     SeparateReasoningReqInput,
     SetInternalStateReq,
     SlowDownReqInput,
+    UnloadLoRAAdapterReqInput,
     UpdateWeightFromDiskReqInput,
     UpdateWeightsFromDistributedReqInput,
     UpdateWeightsFromTensorReqInput,
@@ -595,6 +597,40 @@ async def slow_down(obj: SlowDownReqInput, request: Request):
         return _create_error_response(e)
 
 
+@app.api_route("/load_lora_adapter", methods=["POST"])
+async def load_lora_adapter(obj: LoadLoRAAdapterReqInput, request: Request):
+    """Load a new LoRA adapter without re-launching the server."""
+    result = await _global_state.tokenizer_manager.load_lora_adapter(obj, request)
+
+    if result.success:
+        return ORJSONResponse(
+            result,
+            status_code=HTTPStatus.OK,
+        )
+    else:
+        return ORJSONResponse(
+            result,
+            status_code=HTTPStatus.BAD_REQUEST,
+        )
+
+
+@app.api_route("/unload_lora_adapter", methods=["POST"])
+async def unload_lora_adapter(obj: UnloadLoRAAdapterReqInput, request: Request):
+    """Load a new LoRA adapter without re-launching the server."""
+    result = await _global_state.tokenizer_manager.unload_lora_adapter(obj, request)
+
+    if result.success:
+        return ORJSONResponse(
+            result,
+            status_code=HTTPStatus.OK,
+        )
+    else:
+        return ORJSONResponse(
+            result,
+            status_code=HTTPStatus.BAD_REQUEST,
+        )
+
+
 @app.api_route("/open_session", methods=["GET", "POST"])
 async def open_session(obj: OpenSessionReqInput, request: Request):
     """Open a session, and return its unique session id."""