[Cherry-Pick]【TI-Consisent】Added Metric logits_stats to the ZMQ branch (#6979)

[liuruyan]

Motivation

背景：出于对训推一致性丰富检测指标及长期CI/CE监控考量，对sample之后的logits添加logits_stats(min/max/mean/std)，用来保证确定性及稳定性。

Modifications

数据结构及接口：由于logprob与logits_stat同样是输出的重要检测指标且均从logits计算而来，暂时实现先将logits_stat存入LogprobsTensors数据结构保存，并升级logprob传播链路上相关接口，支持同时透传logits_stats

class LogprobsTensors(NamedTuple):
    """ """

    # [num_reqs, max_num_logprobs + 1]
    logprob_token_ids: paddle.Tensor
    # [num_reqs, max_num_logprobs + 1]
    logprobs: paddle.Tensor
    # [num_reqs]
    selected_token_ranks: paddle.Tensor
    # Logits statistics for each sequence (optional)
    logits_min: Optional[paddle.Tensor] = None  # [num_reqs]
    logits_max: Optional[paddle.Tensor] = None  # [num_reqs]
    logits_mean: Optional[paddle.Tensor] = None  # [num_reqs]
    logits_std: Optional[paddle.Tensor] = None
    ...

FLAG：添加与enable_logprob同级别model_config：self.compute_logits_stats = False，且在server启动时支持配置--compute-logits-stats

注：由于改变了返回字段，导致有些单测无法通过，所以改动单测文件，返回值中提出新增字段（logits_stats ）

Usage or Command

• 本功能暂时只支持ZMQ，流式与非流式测试均可正常返回
• 启动FD服务时需要同时开启--compute-logits-stats,--enable-logprob

export FD_USE_GET_SAVE_OUTPUT_V1=1 
python -m fastdeploy.entrypoints.openai.api_server \
       --enable-logprob \
       --compute-logits-stats \
       ...  # more setting

• 发送请求时需要指定logprobs=True,top_logprobs=0

response = client.chat.completions.create(
    model="null",
    messages=[
        {"role": "system", "content": "I'm a helpful AI assistant."},
        {"role": "user", "content": "把李白的静夜思改写为现代诗"},
    ],
    stream=True,  # False
    max_tokens=100,
    logprobs=True,
    top_logprobs=0
)

Accuracy Tests

本PR不涉及精度修改

Checklist

• Add at least a tag in the PR title.
  • Tag list: [[FDConfig],[APIServer],[Engine], [Scheduler], [PD Disaggregation], [Executor], [Graph Optimization], [Speculative Decoding], [RL], [Models], [Quantization], [Loader], [OP], [KVCache], [DataProcessor], [BugFix], [Docs], [CI], [Optimization], [Feature], [Benchmark], [Others], [XPU], [HPU], [GCU], [DCU], [Iluvatar], [Metax]]
  • You can add new tags based on the PR content, but the semantics must be clear.
• Format your code, run pre-commit before commit.
• Add unit tests. Please write the reason in this PR if no unit tests.
• Provide accuracy results.
• If the current PR is submitting to the release branch, make sure the PR has been submitted to the develop branch, then cherry-pick it to the release branch with the [Cherry-Pick] PR tag.

[paddle-bot]

Thanks for your contribution!

[codecov-commenter]

Codecov Report

❌ Patch coverage is 63.63636% with 20 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (release/2.5@d12aa28). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
fastdeploy/entrypoints/openai/serving_chat.py	48.27%	11 Missing and 4 partials ⚠️
fastdeploy/output/token_processor.py	28.57%	4 Missing and 1 partial ⚠️

Additional details and impacted files

@@              Coverage Diff               @@
##             release/2.5    #6978   +/-   ##
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  Coverage               ?   68.93%           
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  Files                  ?      390           
  Lines                  ?    53763           
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  Hits                   ?    37061           
  Misses                 ?    13981           
  Partials               ?     2721           

Flag	Coverage Δ
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