[RL][Cherry-Pick] Support Fully Async and PrefixCache

[gongshaotian]

Motivation

Origin PR: #6314

Current implementation (does not support PrefixCache)：

PrefixCache Support Solution：

The workflow of asynchronous transmission routing：

ModelRunner（主进程）
multiprocessing.Manager.Queue（主进程 - 子进程任务队列）
StoreProcess (子进程)
├── Main Loop (从 Queue 获取任务)
├── ThreadPoolExecutor (5个工作线程)
│   ├── Worker Thread 1: process_put_task() → 提交协程到事件循环
│   ├── Worker Thread 2: process_clear_store_task() → 提交协程到事件循环
│   └── ...
└── AsyncEventLoopThread (专用线程)
    └── asyncio Event Loop
        ├── 执行: await p2p_client.put()
        ├── 执行: await p2p_client.clear_store()
        └── 执行: await p2p_client.delete_prefix_batch()

Modifications

1. RoutingReplayManager
2. RoutingStore
3. ModelRunner

Usage or Command

Pass

Accuracy Tests

Pass

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 36.21622% with 236 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (develop@6d83dcc). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
...model_executor/layers/moe/routing_indices_cache.py	35.29%	219 Missing and 12 partials ⚠️
fastdeploy/worker/gpu_model_runner.py	50.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             develop    #6599   +/-   ##
==========================================
  Coverage           ?   71.15%           
==========================================
  Files              ?      394           
  Lines              ?    53972           
  Branches           ?     8468           
==========================================
  Hits               ?    38404           
  Misses             ?    12812           
  Partials           ?     2756           

Flag	Coverage Δ
GPU	71.15% <36.21%> (?)

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