Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

infoschema: fix issue of information schema cache miss cause by schema version gap #53445

Merged
merged 5 commits into from
May 27, 2024

Conversation

crazycs520
Copy link
Contributor

@crazycs520 crazycs520 commented May 21, 2024

What problem does this PR solve?

Issue Number: close #53428

Problem Summary: fix issue of information schema cache miss cause by schema version gap

What changed and how does it work?

before this PR

When DDL has empty schema version, will cause cache miss, then stale-read query need to load snapshot schema from TiKV.

image
[2024/05/23 06:15:10.546 +00:00] [INFO] [domain.go:287] ["diff load InfoSchema success"] [currentSchemaVersion=6760] [neededSchemaVersion=6762] ["start time"=2.583049ms] [gotSchemaVersion=6762] [phyTblIDs="[]"] [actionTypes="[]"] [diffTypes="[\"drop table\"]"]
[2024/05/23 06:15:17.869 +00:00] [INFO] [domain.go:287] ["diff load InfoSchema success"] [currentSchemaVersion=6763] [neededSchemaVersion=6765] ["start time"=2.040666ms] [gotSchemaVersion=6765] [phyTblIDs="[10496]"] [actionTypes="[4]"] [diffTypes="[\"drop table\"]"]
[2024/05/23 06:15:18.051 +00:00] [INFO] [domain.go:287] ["diff load InfoSchema success"] [currentSchemaVersion=6765] [neededSchemaVersion=6767] ["start time"=4.321375ms] [gotSchemaVersion=6767] [phyTblIDs="[]"] [actionTypes="[]"] [diffTypes="[\"drop table\"]"]
[2024/05/23 06:15:18.245 +00:00] [INFO] [domain.go:287] ["diff load InfoSchema success"] [currentSchemaVersion=6767] [neededSchemaVersion=6769] ["start time"=3.01603ms] [gotSchemaVersion=6769] [phyTblIDs="[]"] [actionTypes="[]"] [diffTypes="[\"drop table\"]"]

This PR

When DDL has empty schema version, this PR won't have schema cache miss, then won't cause many load snapshot schema operation.

image
[2024/05/23 06:23:45.209 +00:00] [INFO] [domain.go:287] ["diff load InfoSchema success"] [currentSchemaVersion=6777] [neededSchemaVersion=6779] ["start time"=5.409896ms] [gotSchemaVersion=6779] [phyTblIDs="[10502]"] [actionTypes="[4]"] [diffTypes="[\"drop table\"]"]
[2024/05/23 06:23:45.458 +00:00] [INFO] [domain.go:287] ["diff load InfoSchema success"] [currentSchemaVersion=6779] [neededSchemaVersion=6781] ["start time"=2.711853ms] [gotSchemaVersion=6781] [phyTblIDs="[]"] [actionTypes="[]"] [diffTypes="[\"drop table\"]"]
[2024/05/23 06:23:45.650 +00:00] [INFO] [domain.go:287] ["diff load InfoSchema success"] [currentSchemaVersion=6781] [neededSchemaVersion=6783] ["start time"=1.910751ms] [gotSchemaVersion=6783] [phyTblIDs="[]"] [actionTypes="[]"] [diffTypes="[\"drop table\"]"]
[2024/05/23 06:23:49.173 +00:00] [INFO] [domain.go:287] ["diff load InfoSchema success"] [currentSchemaVersion=6784] [neededSchemaVersion=6786] ["start time"=2.511772ms] [gotSchemaVersion=6786] [phyTblIDs="[10505]"] [actionTypes="[4]"] [diffTypes="[\"drop table\"]"]
[2024/05/23 06:23:49.372 +00:00] [INFO] [domain.go:287] ["diff load InfoSchema success"] [currentSchemaVersion=6786] [neededSchemaVersion=6788] ["start time"=2.768253ms] [gotSchemaVersion=6788] [phyTblIDs="[]"] [actionTypes="[]"] [diffTypes="[\"drop table\"]"]
[2024/05/23 06:23:49.590 +00:00] [INFO] [domain.go:287] ["diff load InfoSchema success"] [currentSchemaVersion=6788] [neededSchemaVersion=6790] ["start time"=4.466332ms] [gotSchemaVersion=6790] [phyTblIDs="[]"] [actionTypes="[]"] [diffTypes="[\"drop table\"]"]
[2024/05/23 06:23:53.670 +00:00] [INFO] [domain.go:287] ["diff load InfoSchema success"] [currentSchemaVersion=6791] [neededSchemaVersion=6793] ["start time"=799.389µs] [gotSchemaVersion=6793] [phyTblIDs="[10508]"] [actionTypes="[4]"] [diffTypes="[\"drop table\"]"]
[2024/05/23 06:23:53.872 +00:00] [INFO] [domain.go:287] ["diff load InfoSchema success"] [currentSchemaVersion=6793] [neededSchemaVersion=6795] ["start time"=1.025364ms] [gotSchemaVersion=6795] [phyTblIDs="[]"] [actionTypes="[]"] [diffTypes="[\"drop table\"]"]
[2024/05/23 06:23:54.090 +00:00] [INFO] [domain.go:287] ["diff load InfoSchema success"] [currentSchemaVersion=6795] [neededSchemaVersion=6797] ["start time"=3.549838ms] [gotSchemaVersion=6797] [phyTblIDs="[]"] [actionTypes="[]"] [diffTypes="[\"drop table\"]"]

Check List

Tests

  • Unit test
  • Integration test
  • Manual test (add detailed scripts or steps below)
  • No need to test
    • I checked and no code files have been changed.

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

Please refer to Release Notes Language Style Guide to write a quality release note.

None

…a version gap

Signed-off-by: crazycs520 <crazycs520@gmail.com>
Copy link

ti-chi-bot bot commented May 21, 2024

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

@ti-chi-bot ti-chi-bot bot added do-not-merge/needs-triage-completed release-note-none Denotes a PR that doesn't merit a release note. do-not-merge/work-in-progress Indicates that a PR should not merge because it is a work in progress. size/L Denotes a PR that changes 100-499 lines, ignoring generated files. labels May 21, 2024
Copy link

tiprow bot commented May 21, 2024

Hi @crazycs520. Thanks for your PR.

PRs from untrusted users cannot be marked as trusted with /ok-to-test in this repo meaning untrusted PR authors can never trigger tests themselves. Collaborators can still trigger tests on the PR using /test all.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

@crazycs520 crazycs520 marked this pull request as ready for review May 21, 2024 09:43
@ti-chi-bot ti-chi-bot bot removed the do-not-merge/work-in-progress Indicates that a PR should not merge because it is a work in progress. label May 21, 2024
@crazycs520
Copy link
Contributor Author

@lcwangchao @zimulala @tangenta PTAL

Copy link

codecov bot commented May 21, 2024

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.0142%. Comparing base (53bf76f) to head (f878627).
Report is 24 commits behind head on master.

Additional details and impacted files
@@               Coverage Diff                @@
##             master     #53445        +/-   ##
================================================
+ Coverage   72.5441%   75.0142%   +2.4700%     
================================================
  Files          1505       1505                
  Lines        429846     432958      +3112     
================================================
+ Hits         311828     324780     +12952     
+ Misses        98749      88376     -10373     
- Partials      19269      19802       +533     
Flag Coverage Δ
integration 49.8254% <58.6956%> (?)
unit 71.7725% <100.0000%> (+0.3376%) ⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components Coverage Δ
dumpling 53.9957% <ø> (ø)
parser ∅ <ø> (∅)
br 50.4266% <ø> (+9.0328%) ⬆️

versions = append(versions, ver)
}
sort.Slice(versions, func(i, j int) bool { return versions[i] < versions[j] })
for _, ver := range versions {
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Is removing one version enough?

Copy link
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Because empty schema version rarely appears, I think it's okay to delete just one here.

Signed-off-by: crazycs520 <crazycs520@gmail.com>
Signed-off-by: crazycs520 <crazycs520@gmail.com>
@ti-chi-bot ti-chi-bot bot added the needs-1-more-lgtm Indicates a PR needs 1 more LGTM. label May 21, 2024
Signed-off-by: crazycs520 <crazycs520@gmail.com>
@crazycs520
Copy link
Contributor Author

/retest-required

Copy link

tiprow bot commented May 21, 2024

@crazycs520: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

In response to this:

/retest-required

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.


h.emptySchemaVersions[version] = struct{}{}
if len(h.emptySchemaVersions) > cap(h.cache) {
// remove oldest version.
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

without statistics of how those version are accessed, remove oldest is no better than remove random version, and more complex

Copy link
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

For stale-read query workload, it will always need recent schema version, so remove the oldest version is better.

Copy link
Contributor

@tiancaiamao tiancaiamao left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

How about insert a clone of previous infoschema for the empty schema diff? with its schema version = previous schema version + 1
The data structure and all the other operations can be the same as before.

@ti-chi-bot ti-chi-bot bot added lgtm and removed needs-1-more-lgtm Indicates a PR needs 1 more LGTM. labels May 22, 2024
Copy link

ti-chi-bot bot commented May 22, 2024

[LGTM Timeline notifier]

Timeline:

  • 2024-05-21 12:12:49.549483541 +0000 UTC m=+2173723.306619106: ☑️ agreed by lcwangchao.
  • 2024-05-22 14:03:54.117975959 +0000 UTC m=+2266787.875111530: ☑️ agreed by tiancaiamao.

@crazycs520
Copy link
Contributor Author

How about insert a clone of previous infoschema for the empty schema diff? with its schema version = previous schema version + 1 The data structure and all the other operations can be the same as before.

Nice catch, I try to use methold, but this will need to introduce another TiKV RPC to get the schemaTS of the empty schema version.

@crazycs520
Copy link
Contributor Author

/retest-required

@ti-chi-bot ti-chi-bot bot merged commit 0ac2ad0 into pingcap:master May 27, 2024
23 checks passed
crazycs520 added a commit to crazycs520/tidb that referenced this pull request May 27, 2024
…a version gap (pingcap#53445)

close pingcap#53428

Signed-off-by: crazycs520 <crazycs520@gmail.com>
@crazycs520 crazycs520 added needs-cherry-pick-release-6.5 Should cherry pick this PR to release-6.5 branch. needs-cherry-pick-release-7.1 Should cherry pick this PR to release-7.1 branch. needs-cherry-pick-release-7.5 Should cherry pick this PR to release-7.5 branch. needs-cherry-pick-release-8.1 Should cherry pick this PR to release-8.1 branch. labels May 27, 2024
@crazycs520 crazycs520 deleted the fix-buf-schema-cahce-hole branch May 27, 2024 08:59
ti-chi-bot pushed a commit to ti-chi-bot/tidb that referenced this pull request May 27, 2024
Signed-off-by: ti-chi-bot <ti-community-prow-bot@tidb.io>
@ti-chi-bot
Copy link
Member

In response to a cherrypick label: new pull request created to branch release-6.5: #53583.

@ti-chi-bot
Copy link
Member

In response to a cherrypick label: new pull request created to branch release-8.1: #53584.

@ti-chi-bot
Copy link
Member

In response to a cherrypick label: new pull request created to branch release-7.1: #53585.

ti-chi-bot pushed a commit to ti-chi-bot/tidb that referenced this pull request May 27, 2024
Signed-off-by: ti-chi-bot <ti-community-prow-bot@tidb.io>
ti-chi-bot pushed a commit to ti-chi-bot/tidb that referenced this pull request May 27, 2024
Signed-off-by: ti-chi-bot <ti-community-prow-bot@tidb.io>
@ti-chi-bot
Copy link
Member

In response to a cherrypick label: new pull request created to branch release-7.5: #53586.

crazycs520 added a commit to ti-chi-bot/tidb that referenced this pull request May 27, 2024
RidRisR pushed a commit to RidRisR/tidb that referenced this pull request May 27, 2024
crazycs520 added a commit to ti-chi-bot/tidb that referenced this pull request May 27, 2024
…a version gap (pingcap#53445)

close pingcap#53428

Signed-off-by: crazycs520 <crazycs520@gmail.com>
crazycs520 added a commit to ti-chi-bot/tidb that referenced this pull request May 27, 2024
crazycs520 added a commit to ti-chi-bot/tidb that referenced this pull request May 27, 2024
…a version gap (pingcap#53445)

close pingcap#53428

Signed-off-by: crazycs520 <crazycs520@gmail.com>
ti-chi-bot bot pushed a commit that referenced this pull request May 27, 2024
crazycs520 added a commit that referenced this pull request May 28, 2024
…a version gap (#53445) (#53562)

* infoschema: fix issue of information schema cache miss cause by schema version gap (#53445)

close #53428

Signed-off-by: crazycs520 <crazycs520@gmail.com>
ti-chi-bot bot pushed a commit that referenced this pull request May 28, 2024
ti-chi-bot bot pushed a commit that referenced this pull request May 28, 2024
mittalrishabh pushed a commit to mittalrishabh/tidb that referenced this pull request May 30, 2024
…a version gap (pingcap#53445) (pingcap#53583) (pingcap#97)

close pingcap#53428

Co-authored-by: Ti Chi Robot <ti-community-prow-bot@tidb.io>
ti-chi-bot bot pushed a commit that referenced this pull request Jun 5, 2024
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
approved lgtm needs-cherry-pick-release-6.5 Should cherry pick this PR to release-6.5 branch. needs-cherry-pick-release-7.1 Should cherry pick this PR to release-7.1 branch. needs-cherry-pick-release-7.5 Should cherry pick this PR to release-7.5 branch. needs-cherry-pick-release-8.1 Should cherry pick this PR to release-8.1 branch. ok-to-test Indicates a PR is ready to be tested. release-note-none Denotes a PR that doesn't merit a release note. size/L Denotes a PR that changes 100-499 lines, ignoring generated files.
Projects
None yet
Development

Successfully merging this pull request may close these issues.

stale-read query latency 10x spike cause by information schema cache miss
6 participants