disttask: subtasks rebalance during task execution (#48306)

[ti-chi-bot]

This is an automated cherry-pick of #48306

What problem does this PR solve?

Issue Number: ref #48795 close #47298

Problem Summary:
See issue #47298

What is changed and how it works?

RebalanceSubtasks process flow:

1. find out nodes need to clean subtasks.
2. get subtasks for each node before scaling out.
3. group subtasks for each scheduler.
4. prepare subtasks that need to rebalance to other nodes.
5. rebalance subtasks to other nodes.
6. rebalance rest subtasks evenly to liveNodes.
7. update subtasks and do clean up logic.

Behavior:
see ut in rebalance_test.go

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.

1. first run on 1 tidb then scale out 1 tidb.

2. from 2 tidb to 1 tidb

3. from 1 tidb to 3 tidb

4. from 3 tidb to 1 tidb

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

[ti-chi-bot]

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.
2. AFTER it has been approved by approvers, please wait for the cherry-pick merging approval from triage owners.

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/test-infra repository.

[ti-chi-bot]

@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
idc-jenkins-ci-tidb/build	483a94a	link	true	/test build
idc-jenkins-ci-tidb/check_dev_2	483a94a	link	true	/test check-dev2
idc-jenkins-ci-tidb/check_dev	483a94a	link	true	/test check-dev
idc-jenkins-ci-tidb/unit-test	483a94a	link	true	/test unit-test
idc-jenkins-ci-tidb/mysql-test	483a94a	link	true	/test mysql-test

Full PR test history. Your PR dashboard.

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/test-infra repository. I understand the commands that are listed here.

[Benjamin2037]

LGTM

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Benjamin2037

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

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [Benjamin2037]
• pkg/ddl/OWNERS [Benjamin2037]
• pkg/disttask/OWNERS [Benjamin2037]

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

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-11-30 07:14:41.856044139 +0000 UTC m=+1079710.521270334: ☑️ agreed by Benjamin2037.

[ti-chi-bot]

PR needs rebase.

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/test-infra repository.