[bengbengbalabalabeng]

Purpose of the pull request

What's changed?

• Add a utility to clear all thread locals

Checklist

• I have read the Contributor Guide.
• I have written the necessary doc or comment.
• I have added the necessary unit tests and all cases have passed.

[skytin1004]

I pulled the latest head and reproduced a concurrency failure in the new registry. While one thread was iterating cleanTasks in clearAllThreadLocals(), I registered another cleaner from a second thread. The finishing thread threw ConcurrentModificationException.

Because finish() now calls this registry directly, a successful read or write can fail during cleanup when another thread lazily initializes a utility class and registers its cleaner. Please make registration and iteration thread-safe, for example with CopyOnWriteArrayList or an immutable snapshot under synchronization, and add a deterministic concurrency regression test.

[bengbengbalabalabeng]

I pulled the latest head and reproduced a concurrency failure in the new registry. While one thread was iterating cleanTasks in clearAllThreadLocals(), I registered another cleaner from a second thread. The finishing thread threw ConcurrentModificationException.

Because finish() now calls this registry directly, a successful read or write can fail during cleanup when another thread lazily initializes a utility class and registers its cleaner. Please make registration and iteration thread-safe, for example with CopyOnWriteArrayList or an immutable snapshot under synchronization, and add a deterministic concurrency regression test.

Thanks for the review! I've switched the list to CopyOnWriteArrayList.