fix(cache): move ongoing_prefetch pop after validation to prevent leak

[xiaguan]

There is a high priority bug.

It will cause all prefetch operations to leak, as prefetch operations cannot be released, which subsequently causes hicache to malfunction (due to memory not being freed), and prefetch operations cannot proceed because the prefetch limit is constantly being triggered.

@xiezhq-hermann

Motivation

Modifications

Accuracy Tests

Benchmarking and Profiling

Checklist

• Format your code according to the Format code with pre-commit.
• Add unit tests according to the Run and add unit tests.
• Update documentation according to Write documentations.
• Provide accuracy and speed benchmark results according to Test the accuracy and Benchmark the speed.

[gemini-code-assist]

Summary of Changes

Hello @xiaguan, 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 resolves a critical bug within the cache prefetching logic that caused prefetch operations to leak. This leak led to memory not being freed and prevented new prefetch operations from proceeding due to an incorrectly triggered prefetch limit, ultimately causing hicache to malfunction. The fix ensures that prefetch entries are properly managed and released.

Highlights

• Prevent Cache Leak: The ongoing_prefetch entry is now removed only after validating the prefetch operation's status, specifically after checking if it was issued or can be terminated. Previously, it was removed prematurely, leading to a leak of prefetch operations and associated memory.

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[gemini-code-assist]

Code Review

This pull request addresses a critical memory leak in the prefetch handling logic. The issue stemmed from prematurely removing a prefetch operation from the ongoing_prefetch dictionary before it was determined if the operation could be terminated. This could lead to the operation's resources never being released if it wasn't ready for termination. The fix correctly defers the pop operation until after all checks are complete and the operation is either fully processed or deemed invalid. This ensures that prefetch operations are not lost and their associated memory is properly managed. The change is logical and effectively resolves the described bug.

[huangtingwei9988]

LGTM

[hzh0425]

I've encountered this issue too