api: avoid dead lock if remove operator is not finished

[wk989898]

What problem does this PR solve?

Issue Number: ref #3962

What is changed and how it works?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Questions

Will it cause performance regression or break compatibility?

Do you need to update user documentation, design documentation or monitoring documentation?

Release note

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[ti-chi-bot]

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[gemini-code-assist]

Summary of Changes

Hello @wk989898, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a potential deadlock scenario in the API layer when managing changefeeds. By adjusting the timing of the API lock release in the RemoveChangefeed and PauseChangefeed operations, it ensures that the API is not blocked while waiting for long-running operator tasks to finish. This change improves the overall responsiveness and concurrency of the API.

Highlights

• Deadlock Prevention: Modified the RemoveChangefeed and PauseChangefeed API functions to prevent potential deadlocks by releasing the API lock earlier.
• Concurrency Improvement: The apiLock is now released before waiting for the changefeed stop/pause operation to complete, allowing other API calls to proceed concurrently.

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[gemini-code-assist]

Code Review

This pull request aims to prevent a deadlock by releasing a lock before a long-running operation in RemoveChangefeed and PauseChangefeed. While the intention is correct, the implementation introduces a critical issue: the lock is not released in several early-return error paths within both functions. This will cause the lock to be held indefinitely, leading to a deadlock. I have provided two critical review comments with code suggestions to fix these issues by ensuring the lock is released in all execution paths.

[ti-chi-bot]

@wk989898: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-unit-test-next-gen	09008a3	link	false	/test pull-unit-test-next-gen
pull-unit-test	09008a3	link	true	/test pull-unit-test

Full PR test history. Your PR dashboard.

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