cluster: speed scheduler exit (#4148)

[ti-chi-bot]

This is an automated cherry-pick of #4148

What problem does this PR solve?

closed #4146 speed schedule exit

What is changed and how it works?

pause scheduler after accept stop signal, and do not loop

Check List

Tests

• Manual test (add detailed scripts or steps below)

Code changes

Side effects

Related changes

• Need to cherry-pick to the release branch

Release note

speed scheduler exit  

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• JmPotato
• nolouch

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[codecov]

Codecov Report

Merging #4199 (1aed898) into release-5.2 (8afd38d) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@               Coverage Diff               @@
##           release-5.2    #4199      +/-   ##
===============================================
+ Coverage        74.61%   74.63%   +0.02%     
===============================================
  Files              250      250              
  Lines            25538    25542       +4     
===============================================
+ Hits             19054    19063       +9     
- Misses            4789     4794       +5     
+ Partials          1695     1685      -10     

Flag	Coverage Δ
unittests	74.63% <100.00%> (+0.02%)	⬆️

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

Impacted Files	Coverage Δ
server/cluster/cluster.go	82.69% <100.00%> (ø)
server/cluster/coordinator.go	73.82% <100.00%> (+0.91%)	⬆️
server/schedulers/shuffle_hot_region.go	55.55% <0.00%> (-10.11%)	⬇️
pkg/etcdutil/etcdutil.go	84.70% <0.00%> (-3.53%)	⬇️
server/election/leadership.go	83.90% <0.00%> (-3.45%)	⬇️
server/member/member.go	63.10% <0.00%> (-2.14%)	⬇️
server/schedule/operator_controller.go	83.56% <0.00%> (-1.19%)	⬇️
server/schedule/operator/step.go	68.10% <0.00%> (-1.00%)	⬇️
pkg/btree/btree.go	85.78% <0.00%> (-0.97%)	⬇️
client/base_client.go	84.37% <0.00%> (-0.53%)	⬇️
... and 9 more

---

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[nolouch]

/merge

[ti-chi-bot]

@nolouch: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

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[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 1aed898

[ti-chi-bot]

@ti-chi-bot: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

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.