Storages: Splitting DMFileReaderPool to reduce lock contention (#9126)

[ti-chi-bot]

This is an automated cherry-pick of #9126

What problem does this PR solve?

Issue Number: close #9125

Problem Summary:

What is changed and how it works?

Reduce the lock contention on DMFileReaderPool::mtx by splitting the dmfiles by hash(file_path) of 16

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
  • Run simple queries (select max(k) from sbtest1) concurrently.
  • Time consumption unit: ms.

Concurrency	Master	This PR
1	27	25
2	28	29
4	46	46
8	72	77
16	124	97
32	232	160
64	450	327

• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Improve the short queries performance under high concurrency by reducing the lock contention

[JinheLin]

/run-all-tests

[JaySon-Huang]

/run-all-tests

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JaySon-Huang, JinheLin

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Needs approval from an approver in each of these files:

• OWNERS [JaySon-Huang,JinheLin]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-08-27 04:02:31.843649004 +0000 UTC m=+842946.978099124: ☑️ agreed by JaySon-Huang.
• 2024-08-27 06:54:45.815046065 +0000 UTC m=+853280.949496183: ☑️ agreed by JinheLin.