[BugFix] Fix get_tasks returns empty task list bug

[liyonghua0910]

Motivation

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Modifications

Usage or Command

Accuracy Tests

Checklist

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[paddle-bot]

Thanks for your contribution!

[PaddlePaddle-bot]

🤖 AI Code Review | 2026-04-22 15:45:50

📋 Review 摘要

PR 概述：修复 TP（张量并行）模式下 get_tasks() 因竞态条件返回空任务列表的 Bug。
变更范围：fastdeploy/worker/worker_process.py — Worker 事件循环同步逻辑
影响面 Tag：[Engine]

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📝 PR 规范检查

PR 标题含有效 [BugFix] Tag，但 Motivation / Modifications 正文均为空，未描述变更内容与影响面。建议补充（可直接复制）：

## Motivation
在 TP（张量并行）模式下，多 TP rank 共享任务队列。`get_tasks()` 只有在所有客户端
读取完毕后才清空任务列表。若 rank-0 在 rank-N 完成 `get_tasks()` 并重置
`exist_task_signal` 之前回到 while 循环顶部，会再次进入 if 块并调用 `get_tasks()`。
此时任务列表已被清空，导致 `tasks=[]`，触发 `assert len(tasks) > 0`。

## Modifications
在 `get_tasks()` 和信号重置之后、EP barrier 之前，增加一次 `_tp_barrier_wait()`，
确保所有 TP rank 同步后才能继续，消除竞态窗口。

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问题

级别	文件	概述
🟡 建议	worker_process.py:551	新增 barrier 缺少注释说明意图
🟡 建议	—	Bug fix 无回归测试

关于回归测试：tests/worker/test_worker_process.py 中已有 _tp_barrier_wait 的 Mock，建议补充一个模拟 rank-0 提前回到循环的竞态场景测试，防止未来引入相同问题。

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总体评价

修复逻辑正确，在 get_tasks() 和信号重置之后新增 _tp_barrier_wait() 是消除该竞态的最小代价方案，与文件中其他 barrier 的使用模式一致。建议补充 PR 描述和行内注释，提高可维护性。

[PaddlePaddle-bot]

🟡 建议 建议补充注释说明此 barrier 的作用

此行是竞态修复的关键点，但缺少说明 为什么 需要在这里同步。建议参考上方第 484-485 行的注释风格，补充如下：

# Synchronize all TP workers after get_tasks() and signal reset to prevent
# rank-0 from looping back and calling get_tasks() again before rank-N resets
# exist_task_signal, which would result in an empty task list.
self._tp_barrier_wait() if tp_size > 1 else None

[codecov-commenter]

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