Fix runtime.generate when sampling param is not passed

[ByronHsu]

Motivation

import sglang as sgl

model_path = "/shared/public/models/Qwen/Qwen2.5-1.5B-Instruct/"

if __name__ == "__main__":
    runtime = sgl.Runtime(model_path=model_path)

    print(runtime.generate("Who is Steve Jobs?"))
    runtime.shutdown()

The above code fails with

  File "/home/jobuser/sglang/python/sglang/srt/server.py", line 184, in generate_request
    ret = await tokenizer_manager.generate_request(obj, request).__anext__()
  File "/home/jobuser/sglang/python/sglang/srt/managers/tokenizer_manager.py", line 152, in generate_request
    obj.post_init()
  File "/home/jobuser/sglang/python/sglang/srt/managers/io_struct.py", line 83, in post_init
    self.parallel_sample_num = self.sampling_params[0].get("n", 1)

This is because sampling_params == None falls under to

sglang/python/sglang/srt/managers/io_struct.py

Line 82 in 8ac3ccc

else: # isinstance(self.sampling_params, list):

Modifications

Change line80 to elif

Test

After the fix, the above example can produce

{"text": " Steve Jobs is a renowned American entrepreneur, co-founder, president and CEO of Apple Inc., and a key force behind its growth and success. He has a significant impact on both the business world and popular culture. In addition to co-founding Apple Inc., Jobs was also the chairman and CEO of Pixar Animation Studios, was a cofounder of NeXT, and co-founder of the technology company Adobe. He is also regarded as one of the most influential figures in the technology industry of his time. More significantly, Jobs was a pioneer visionary in the technology industry, and a driving force behind the digital revolution. His contributions to the creation and development", "meta_info": {"prompt_tokens": 5, "completion_tokens": 128, "completion_tokens_wo_jump_forward": 128, "finish_reason": {"type": "length", "length": 128}, "id": "14fe8aff836d427aba0a262fcf25c721"}, "index": 0}

Checklist

• Format your code according to the Contributor Guide.
• Add unit tests as outlined in the Contributor Guide.
• Update documentation as needed, including docstrings or example tutorials.