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GC: remove compact on split (#18500)#18733

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GC: remove compact on split (#18500)#18733
ti-chi-bot wants to merge 1 commit intotikv:release-8.1from
ti-chi-bot:cherry-pick-18500-to-release-8.1

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@ti-chi-bot ti-chi-bot commented Jul 21, 2025

This is an automated cherry-pick of #18500

What is changed and how it works?

Issue Number: Close #18451

What's Changed:

Remove compaction scheduling on split key not found error. 

Split key not found error is usually returned when a region only has a few keys but a large number of stale MVCC versions.
This was the incentive of scheduling a compaction on split error. However, this solution brings a more serious problem, i.e. worker threads starvation.
We don't really need this extra compaction, we expect that, after the compaction optimization is done, this MVCC accumulation issue would be mitigated. So, once the "split key not found" occurs, we just rely on the CheckThenCompact to resolve it.

Related changes

  • PR to update pingcap/docs/pingcap/docs-cn:
  • Need to cherry-pick to the release branch

Check List

Tests

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

Side effects

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

Release note

None

@ti-chi-bot ti-chi-bot added dco-signoff: yes Indicates the PR's author has signed the dco. do-not-merge/hold Indicates that a PR should not merge because someone has issued a /hold command. release-note-none Denotes a PR that doesn't merit a release note. size/XL Denotes a PR that changes 500-999 lines, ignoring generated files. type/cherry-pick-for-release-8.1 This PR is cherry-picked to release-8.1 from a source PR. labels Jul 21, 2025
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ti-chi-bot bot commented Jul 21, 2025

This cherry pick PR is for a release branch and has not yet been approved by triage owners.
Adding the do-not-merge/cherry-pick-not-approved label.

To merge this cherry pick:

  1. It must be approved by the approvers firstly.
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ti-chi-bot commented Jul 21, 2025

@v01dstar This PR has conflicts, I have hold it.
Please resolve them or ask others to resolve them, then comment /unhold to remove the hold label.

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@ti-chi-bot ti-chi-bot bot added size/L Denotes a PR that changes 100-499 lines, ignoring generated files. and removed size/XL Denotes a PR that changes 500-999 lines, ignoring generated files. labels Jul 21, 2025
@v01dstar v01dstar force-pushed the cherry-pick-18500-to-release-8.1 branch 2 times, most recently from ca9b8c5 to 70fa011 Compare August 5, 2025 18:42
@ti-chi-bot ti-chi-bot bot added size/XL Denotes a PR that changes 500-999 lines, ignoring generated files. and removed size/L Denotes a PR that changes 100-499 lines, ignoring generated files. labels Aug 5, 2025
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ti-chi-bot bot commented Aug 6, 2025

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: v01dstar

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@ti-chi-bot ti-chi-bot bot added the needs-1-more-lgtm Indicates a PR needs 1 more LGTM. label Aug 6, 2025
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ti-chi-bot bot commented Aug 6, 2025

[LGTM Timeline notifier]

Timeline:

  • 2025-08-06 18:06:26.377135019 +0000 UTC m=+464296.519896195: ☑️ agreed by v01dstar.

@ti-chi-bot ti-chi-bot bot added the approved label Aug 6, 2025
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GC: remove compact on split (tikv#18500)
6160325 
close tikv#18451

Remove compaction scheduling on split key not found error.

Split key not found error is usually returned when a region only has a few keys but a large number of stale MVCC versions.
This was the incentive of scheduling a compaction on split error. However, this solution brings a more serious problem, i.e. worker threads starvation.
We don't really need this extra compaction, we expect that, after the compaction optimization is done, this MVCC accumulation issue would be mitigated. So, once the "split key not found" occurs, we just rely on the CheckThenCompact to resolve it.

Signed-off-by: Yang Zhang <yang.zhang@pingcap.com>
@v01dstar v01dstar force-pushed the cherry-pick-18500-to-release-8.1 branch from 70fa011 to 6160325 Compare September 30, 2025 21:19
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ti-chi-bot bot commented Sep 30, 2025

@ti-chi-bot: 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-check-deps 6160325 link true /test pull-check-deps
pull-unit-test 6160325 link true /test pull-unit-test

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