[Misc] Enhance offline_inference to support user-configurable paramet… (#10392)

Signed-off-by: wchen61 <wchen61@foxmail.com>

examples/offline_inference.py

+from dataclasses import asdict
+
 from vllm import LLM, SamplingParams
+from vllm.engine.arg_utils import EngineArgs
+from vllm.utils import FlexibleArgumentParser
+
 
-# Sample prompts.
-prompts = [
+def get_prompts(num_prompts: int):
+    # The default 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 = SamplingParams(temperature=0.8, top_p=0.95)
-
-# Create an LLM.
-llm = LLM(model="facebook/opt-125m")
-# Generate texts from the prompts. The output is a list of RequestOutput objects
-# that contain the prompt, generated text, and other information.
-outputs = llm.generate(prompts, sampling_params)
-# Print the outputs.
-for output in outputs:
+    ]
+
+    if num_prompts != len(prompts):
+        prompts = (prompts * ((num_prompts // len(prompts)) + 1))[:num_prompts]
+
+    return prompts
+
+
+def main(args):
+    # Create prompts
+    prompts = get_prompts(args.num_prompts)
+
+    # Create a sampling params object.
+    sampling_params = SamplingParams(n=args.n,
+                                     temperature=args.temperature,
+                                     top_p=args.top_p,
+                                     top_k=args.top_k,
+                                     max_tokens=args.max_tokens)
+
+    # Create an LLM.
+    # The default model is 'facebook/opt-125m'
+    engine_args = EngineArgs.from_cli_args(args)
+    llm = LLM(**asdict(engine_args))
+
+    # Generate texts from the prompts.
+    # The output is a list of RequestOutput objects
+    # that contain the prompt, generated text, and other information.
+    outputs = llm.generate(prompts, sampling_params)
+    # Print the outputs.
+    for output in outputs:
         prompt = output.prompt
         generated_text = output.outputs[0].text
         print(f"Prompt: {prompt!r}, Generated text: {generated_text!r}")
+
+
+if __name__ == '__main__':
+    parser = FlexibleArgumentParser()
+    parser = EngineArgs.add_cli_args(parser)
+    group = parser.add_argument_group("SamplingParams options")
+    group.add_argument("--num-prompts",
+                       type=int,
+                       default=4,
+                       help="Number of prompts used for inference")
+    group.add_argument("--max-tokens",
+                       type=int,
+                       default=16,
+                       help="Generated output length for sampling")
+    group.add_argument('--n',
+                       type=int,
+                       default=1,
+                       help='Number of generated sequences per prompt')
+    group.add_argument('--temperature',
+                       type=float,
+                       default=0.8,
+                       help='Temperature for text generation')
+    group.add_argument('--top-p',
+                       type=float,
+                       default=0.95,
+                       help='top_p for text generation')
+    group.add_argument('--top-k',
+                       type=int,
+                       default=-1,
+                       help='top_k for text generation')
+
+    args = parser.parse_args()
+    main(args)