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GC: remove compact on split (#18500)#18731

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ti-chi-bot[bot] merged 1 commit intotikv:release-8.5from
ti-chi-bot:cherry-pick-18500-to-release-8.5
Sep 17, 2025
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GC: remove compact on split (#18500)#18731
ti-chi-bot[bot] merged 1 commit intotikv:release-8.5from
ti-chi-bot:cherry-pick-18500-to-release-8.5

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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 bot added release-note-none Denotes a PR that doesn't merit a release note. do-not-merge/cherry-pick-not-approved labels Jul 21, 2025
@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. size/XL Denotes a PR that changes 500-999 lines, ignoring generated files. type/cherry-pick-for-release-8.5 This PR is cherry-picked to release-8.5 from a source PR. labels Jul 21, 2025
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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-8.5 branch 2 times, most recently from 4d36680 to df85f93 Compare September 16, 2025 21:43
@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 Sep 16, 2025
@v01dstar v01dstar force-pushed the cherry-pick-18500-to-release-8.5 branch 3 times, most recently from 8a3604c to 22690bc Compare September 16, 2025 22:00
@ti-chi-bot ti-chi-bot bot added needs-1-more-lgtm Indicates a PR needs 1 more LGTM. cherry-pick-approved Cherry pick PR approved by release team. and removed do-not-merge/cherry-pick-not-approved labels Sep 16, 2025
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GC: remove compact on split (tikv#18500)
7c8f087 
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-8.5 branch from 22690bc to 7c8f087 Compare September 17, 2025 18:46
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v01dstar commented Sep 17, 2025

/test

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v01dstar commented Sep 17, 2025

/test pull-unit-test

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v01dstar commented Sep 17, 2025

/unhold

Connor1996
Connor1996 approved these changes Sep 17, 2025
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LGTM

@ti-chi-bot ti-chi-bot bot added lgtm and removed do-not-merge/hold Indicates that a PR should not merge because someone has issued a /hold command. labels Sep 17, 2025
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ti-chi-bot bot commented Sep 17, 2025

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Connor1996, v01dstar

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@ti-chi-bot ti-chi-bot bot added approved and removed needs-1-more-lgtm Indicates a PR needs 1 more LGTM. labels Sep 17, 2025
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ti-chi-bot bot commented Sep 17, 2025

[LGTM Timeline notifier]

Timeline:

  • 2025-09-16 22:20:27.314771739 +0000 UTC m=+1004693.874653246: ☑️ agreed by v01dstar.
  • 2025-09-17 21:11:18.354720321 +0000 UTC m=+47839.833300978: ☑️ agreed by Connor1996.

@ti-chi-bot ti-chi-bot bot merged commit 65eabb3 into tikv:release-8.5 Sep 17, 2025
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@ti-chi-bot ti-chi-bot bot deleted the cherry-pick-18500-to-release-8.5 branch September 17, 2025 21:14
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