Support token ids in `engine.generate` (#1820)

examples/runtime/engine/input_ids.py

+"""
+This example demonstrates how to provide tokenized ids as input instead of text prompt
+"""
+
+import sglang as sgl
+from sglang.srt.hf_transformers_utils import get_tokenizer
+
+MODEL_PATH = "meta-llama/Llama-3.1-8B-Instruct"
+
+def main():
+    # Sample prompts.
+    prompts = [
+        "Hello, my name is",
+        "The president of the United States is",
+        "The capital of France is",
+        "The future of AI is",
+    ]
+    # Create a sampling params object.
+    sampling_params = {"temperature": 0.8, "top_p": 0.95}
+
+    # Tokenize inputs
+    tokenizer = get_tokenizer(MODEL_PATH)
+    token_ids_list = [tokenizer.encode(prompt) for prompt in prompts]
+    
+    # Create an LLM.
+    # You can also specify `skip_tokenizer_init=True`, but it requires explicit detokenization at the end
+    llm = sgl.Engine(model_path=MODEL_PATH)
+
+    outputs = llm.generate(input_ids=token_ids_list, sampling_params=sampling_params)
+    # Print the outputs.
+    for prompt, output in zip(prompts, outputs):
+        print("===============================")
+        print(f"Prompt: {prompt}\nGenerated Text: {output['text']}")
+
+
+# The __main__ condition is necessary here because we use "spawn" to create subprocesses
+# Spawn starts a fresh program every time, if there is no __main__, it will run into infinite loop to keep spawning processes from sgl.Engine
+if __name__ == "__main__":
+    main()
\ No newline at end of file

python/sglang/srt/server.py

@@ -742,18 +742,20 @@ class Engine:
 
     def generate(
         self,
-        prompt: Union[str, List[str]],
+        # The input prompt. It can be a single prompt or a batch of prompts.
+        prompt: Optional[Union[List[str], str]] = None,
         sampling_params: Optional[Dict] = None,
+        # The token ids for text; one can either specify text or input_ids.
+        input_ids: Optional[Union[List[List[int]], List[int]]] = None,
         return_logprob: Optional[Union[List[bool], bool]] = False,
         logprob_start_len: Optional[Union[List[int], int]] = None,
         top_logprobs_num: Optional[Union[List[int], int]] = None,
         lora_path: Optional[List[Optional[str]]] = None,
         stream: bool = False,
     ):
-        # TODO (ByronHsu): refactor to reduce the duplicated code
-
         obj = GenerateReqInput(
             text=prompt,
+            input_ids=input_ids,
             sampling_params=sampling_params,
             return_logprob=return_logprob,
             logprob_start_len=logprob_start_len,
@@ -791,8 +793,11 @@ class Engine:
 
     async def async_generate(
         self,
-        prompt: Union[str, List[str]],
+        # The input prompt. It can be a single prompt or a batch of prompts.
+        prompt: Optional[Union[List[str], str]] = None,
         sampling_params: Optional[Dict] = None,
+        # The token ids for text; one can either specify text or input_ids.
+        input_ids: Optional[Union[List[List[int]], List[int]]] = None,
         return_logprob: Optional[Union[List[bool], bool]] = False,
         logprob_start_len: Optional[Union[List[int], int]] = None,
         top_logprobs_num: Optional[Union[List[int], int]] = None,
@@ -801,6 +806,7 @@ class Engine:
     ):
         obj = GenerateReqInput(
             text=prompt,
+            input_ids=input_ids,
             sampling_params=sampling_params,
             return_logprob=return_logprob,
             logprob_start_len=logprob_start_len,

test/srt/test_srt_engine.py

@@ -9,6 +9,7 @@ import unittest
 from types import SimpleNamespace
 
 import sglang as sgl
+from sglang.srt.hf_transformers_utils import get_tokenizer
 from sglang.test.few_shot_gsm8k_engine import run_eval
 from sglang.test.test_utils import DEFAULT_MODEL_NAME_FOR_TEST
 
@@ -106,6 +107,28 @@ class TestSRTEngine(unittest.TestCase):
         metrics = run_eval(args)
         assert metrics["accuracy"] > 0.7
 
+    def test_5_prompt_input_ids_consistency(self):
+        prompt = "The capital of UK is"
+
+
+        model_path = DEFAULT_MODEL_NAME_FOR_TEST
+        engine = sgl.Engine(model_path=model_path, random_seed=42, log_level="error")
+        sampling_params = {"temperature": 0, "max_new_tokens": 8}
+        out1 = engine.generate(prompt, sampling_params)["text"]
+
+        tokenizer = get_tokenizer(model_path)
+        token_ids = tokenizer.encode(prompt)
+        out2 = engine.generate(input_ids=token_ids, sampling_params=sampling_params)["text"]
+
+        engine.shutdown()
+
+        print("==== Answer 1 ====")
+        print(out1)
+
+        print("==== Answer 2 ====")
+        print(out2)
+        assert out1 == out2, f"{out1} != {out2}"
+
 
 if __name__ == "__main__":
     unittest.main()