fix TestDedup2, cherry-pick #16301

[jiangxinmeng1]

What type of PR is this?

• API-change
• BUG
• Improvement
• Documentation
• Feature
• Test and CI
• Code Refactoring

Which issue(s) this PR fixes:

issue #13881

What this PR does / why we need it:

Fix data race in TestDedup2

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[matrix-meow]

@jiangxinmeng1 Thanks for your contributions!

Pull Request Review:

Title:

The title of the pull request is clear and concise, indicating that the PR is fixing an issue related to TestDedup2 by cherry-picking changes from another commit (#16301).

Body:

The body of the pull request provides relevant information about the type of PR (BUG), the specific issue it fixes (issue #13881), and the reason for the PR (Fix data race in TestDedup2). It would be beneficial to include more details about the data race issue for better context.

Changes:

1. In the MergeExecutor struct in executor.go, the changes involve modifying the factory function within the ExecuteFor method. The code change now assigns the result of jobs.NewMergeObjectsTask to task and err variables separately, then adds an observer to the task before returning it along with the error. This change aims to address a data race issue by adding the observer after creating the task.

Issues/Problems:

1. Data Race Issue:
   • The original code had a potential data race issue where the observer was added to the task before the task was returned. This could lead to a race condition if the task is accessed concurrently by multiple goroutines.
   • Suggestion: To address this, the observer should be added to the task after creating it to ensure thread safety and prevent data race conditions.

Suggestions for Improvement:

1. Observer Addition:
   • Move the task.AddObserver(e) statement after the task has been created and before returning it in the factory function to ensure that the observer is added in a safe sequence.
   • Optimization: Consider refactoring the code to ensure that the observer is added in a consistent and thread-safe manner to prevent any potential race conditions.

General Feedback:

• It would be beneficial to provide more detailed information in the PR body about the nature of the data race issue and how the code changes effectively resolve it.
• Consider adding comments in the code to explain the rationale behind the changes made, especially regarding the data race fix.

By addressing the data race issue and ensuring proper sequencing of operations, the code quality and reliability can be improved.