[Executor] Add timeout task to async scheduler to achieve timeout feature.

[thy09]

Description

Improve the timeout handling of async scheduler.

Before:
The async nodes would be keep running until the process is killed.

After:
The async function would got an asyncio.CanceledError, then the line raises LineExecutionTimeoutError.

This pull request introduces changes in the src/promptflow-core/promptflow/executor/_async_nodes_scheduler.py and src/promptflow-core/promptflow/executor/flow_executor.py files to handle line execution timeouts. The Optional type has been imported and a timeout_seconds parameter has been added to the execute and _execute_with_thread_pool methods. A timeout mechanism has been implemented in _execute_with_thread_pool to cancel tasks that exceed the specified timeout. A cancel_tasks method has also been added to cancel tasks and yield control to the event loop for cleanup. The LineExecutionTimeoutError exception is raised when a timeout occurs.

Changes to handle line execution timeouts:

• src/promptflow-core/promptflow/executor/_async_nodes_scheduler.py: Imported Optional type and added timeout_seconds parameter to execute and _execute_with_thread_pool methods. Implemented timeout mechanism in _execute_with_thread_pool and added cancel_tasks method to cancel tasks and yield control to the event loop for cleanup. Raised LineExecutionTimeoutError when timeout occurs. [1] [2] [3] [4] [5] [6]
• src/promptflow-core/promptflow/executor/flow_executor.py: Passed self._line_timeout_sec as timeout_seconds to scheduler.execute method.

All Promptflow Contribution checklist:

• The pull request does not introduce [breaking changes].
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.
• Create an issue and link to the pull request to get dedicated review from promptflow team. Learn more: suggested workflow.

General Guidelines and Best Practices

• Title of the pull request is clear and informative.
• There are a small number of commits, each of which have an informative message. This means that previously merged commits do not appear in the history of the PR. For more information on cleaning up the commits in your PR, see this page.

Testing Guidelines

• Pull request includes test coverage for the included changes.

[github-actions]

promptflow SDK CLI Azure E2E Test Result heta/add-timeout-handling-for-async

  4 files    4 suites   4m 11s ⏱️
242 tests 205 ✅  37 💤 0 ❌
968 runs  820 ✅ 148 💤 0 ❌

Results for commit e6e8477.

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[github-actions]

promptflow-core test result

0 tests   0 ✅  0s ⏱️
0 suites  0 💤
0 files    0 ❌

Results for commit e6e8477.

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[github-actions]

SDK CLI Global Config Test Result heta/add-timeout-handling-for-async

6 tests   6 ✅  1m 14s ⏱️
1 suites  0 💤
1 files    0 ❌

Results for commit e6e8477.

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[github-actions]

Executor Unit Test Result heta/add-timeout-handling-for-async

796 tests   796 ✅  3m 45s ⏱️
  1 suites    0 💤
  1 files      0 ❌

Results for commit e6e8477.

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[github-actions]

Executor E2E Test Result heta/add-timeout-handling-for-async

243 tests   238 ✅  5m 34s ⏱️
  1 suites    5 💤
  1 files      0 ❌

Results for commit e6e8477.

♻️ This comment has been updated with latest results.

[github-actions]

SDK CLI Test Result heta/add-timeout-handling-for-async

    4 files      4 suites   1h 3m 1s ⏱️
  715 tests   674 ✅  41 💤 0 ❌
2 860 runs  2 696 ✅ 164 💤 0 ❌

Results for commit e6e8477.

♻️ This comment has been updated with latest results.