[BugFix] reset exist tasks signal in clear_data

[liyonghua0910]

Motivation

EngineWorkerQueue.clear_data() cleared queued tasks and reset client_read_flag, but it did not reset the exist_task signal.

This could leave the queue in an inconsistent state where exist_tasks() still returned true after the task payload had already been cleared. In that case, workers could still enter the get_tasks() path and observe
an empty task list, which may trigger downstream assertion failures.

This PR fixes the queue state inconsistency by resetting the exist_task signal together with queue cleanup.

Modifications

• Update EngineWorkerQueue.clear_data() to reset the exist_task signal when clearing the queue
• Keep queue payload state and task-existence state consistent during cleanup
• Prevent workers from observing stale queue-available state after forced clear operations

Usage or Command

This PR is a bug fix. No new usage is introduced.

Accuracy Tests

This change does not modify model forward logic, kernel behavior, or output generation semantics.

Accuracy impact: none expected.

Checklist

• Add at least a tag in the PR title.
• 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!

[fastdeploy-bot]

🤖 AI Code Review | 2026-03-31 19:47 CST

📋 Review 摘要

PR 概述：修复 EngineWorkerQueue.clear_data() 未重置 exist_task 信号导致的队列状态不一致问题
变更范围：inter_communicator/engine_worker_queue.py, worker/worker_process.py
影响面 Tag：[Engine] [BugFix]

问题

未发现阻塞性问题。

总体评价

本 PR 修复了队列状态不一致的 bug，代码实现正确，与现有的 set_exist_tasks() 方法逻辑一致。continue 缩进调整和日志级别降级也是合理的优化。建议补充单元测试以覆盖此场景。

[codecov-commenter]

Codecov Report

❌ Patch coverage is 40.00000% with 3 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (develop@dd2aa10). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
...stdeploy/inter_communicator/engine_worker_queue.py	33.33%	1 Missing and 1 partial ⚠️
fastdeploy/worker/worker_process.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             develop    #7111   +/-   ##
==========================================
  Coverage           ?   73.98%           
==========================================
  Files              ?      402           
  Lines              ?    56576           
  Branches           ?     8942           
==========================================
  Hits               ?    41856           
  Misses             ?    11780           
  Partials           ?     2940           

Flag	Coverage Δ
GPU	73.98% <40.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[EmmonsCurse]

❌ Cherry-pick failed: Conflicts detected when cherry-picking to release/2.4. Please resolve manually.

[EmmonsCurse]

❌ Cherry-pick failed: Conflicts detected when cherry-picking to release/2.5. Please resolve manually.