sessionctx: fix a deadlock when set tidb_restricted_read_only = true

[Defined2014]

What problem does this PR solve?

Issue Number: close #55373, close #53822,

Problem Summary: follow #40283

What changed and how does it work?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)

run shell below, reach more than 10000

count=0
while true; do
mysql -h 127.0.0.1 -P 4000 -u root -e "set global tidb_restricted_read_only = 1;set global tidb_restricted_read_only = 0;";
count=$((count+1))
echo "$count"
done

• 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

[tiprow]

Hi @Defined2014. 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.

Details

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.

[codecov]

Codecov Report

❌ Patch coverage is 40.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.1637%. Comparing base (bab3667) to head (6f1fc8c).
⚠️ Report is 2226 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #55407        +/-   ##
================================================
+ Coverage   74.9822%   75.1637%   +0.1815%     
================================================
  Files          1576       1577         +1     
  Lines        365580     443312     +77732     
================================================
+ Hits         274120     333210     +59090     
- Misses        71731      90020     +18289     
- Partials      19729      20082       +353     

Flag	Coverage Δ
integration	49.7214% <40.0000%> (?)
unit	72.8833% <40.0000%> (-1.7523%)	⬇️

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

Components	Coverage Δ
dumpling	∅ <ø> (∅)
parser	∅ <ø> (∅)
br	53.3257% <ø> (+4.6624%)	⬆️

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[Defined2014]

/retest

[tiprow]

@Defined2014: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

Details

In response to this:

/retest

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.

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-08-14 06:54:51.915812813 +0000 UTC m=+337376.619282451: ☑️ agreed by hawkingrei.
• 2024-08-14 08:23:42.352758852 +0000 UTC m=+342707.056228508: ☑️ agreed by CbcWestwolf.

[tiprow]

@Defined2014: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
fast_test_tiprow	6f1fc8c	link	true	/test fast_test_tiprow

Full PR test history. Your PR dashboard.

Details

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. I understand the commands that are listed here.

[easonn7]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: CbcWestwolf, easonn7, hawkingrei

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Details

Needs approval from an approver in each of these files:

• pkg/sessionctx/variable/OWNERS [easonn7]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[Defined2014]

/retest

[tiprow]

@Defined2014: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

Details

In response to this:

/retest

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.

[Defined2014]

/retest

[tiprow]

@Defined2014: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

Details

In response to this:

/retest

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.

[Defined2014]

/retest

[tiprow]

@Defined2014: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

Details

In response to this:

/retest

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.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #62744.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #62745.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #62746.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.1: #62747.

[ti-chi-bot]

In response to a cherrypick label: failed to apply #55407 on top of branch "release-8.5":

failed to git commit: exit status 1

[YangKeao]

This bug may happen when setting any global variables after setting tidb_restricted_read_only. Therefore, I'll cherry-pick it back to all LTS versions.

[YangKeao]

/cherry-pick release-6.5-20241112-v6.5.11

[ti-chi-bot]

@YangKeao: new pull request created to branch release-6.5-20241112-v6.5.11: #63515.

Details

In response to this:

/cherry-pick release-6.5-20241112-v6.5.11

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 ti-community-infra/tichi repository.