fake(engine): add cached checkpoint in job master

[amyangfei]

What problem does this PR solve?

Issue Number: close #6598

What is changed and how it works?

Cache checkpoint in job master, if part of workers are offline, keep the old value of them.

Check List

Tests

• Unit test
• Integration test

Questions

Will it cause performance regression or break compatibility?

Do you need to update user documentation, design documentation or monitoring documentation?

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• CharlesCheung96
• maxshuang

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

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

Reviewer can indicate their review by submitting an approval review.
Reviewer can cancel approval by submitting a request changes review.

[amyangfei]

/run-check-issue-triage-complete

[amyangfei]

passed chaos test in: https://github.com/pingcap/tiflow/actions/runs/2789584041

[maxshuang]

@amyangfei Could you explain more about this unstable test? I think I don't real get the point.

[amyangfei]

@amyangfei Could you explain more about this unstable test? I think I don't real get the point.

The root cause was explained in the original issue. @maxshuang

[codecov-commenter]

Codecov Report

Merging #6599 (91e43db) into master (2ea67ba) will increase coverage by 0.0023%.
The diff coverage is 88.6792%.

❗ Current head 91e43db differs from pull request most recent head 8dc9f4f. Consider uploading reports for the commit 8dc9f4f to get more accurate results

Flag	Coverage Δ
cdc	65.9174% <71.4285%> (+0.0493%)	⬆️
dm	51.8930% <ø> (-0.1487%)	⬇️
engine	62.7706% <92.3664%> (+0.2345%)	⬆️

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

@@               Coverage Diff                @@
##             master      #6599        +/-   ##
================================================
+ Coverage   59.2138%   59.2161%   +0.0023%     
================================================
  Files           780        780                
  Lines         88405      88312        -93     
================================================
- Hits          52348      52295        -53     
+ Misses        31415      31378        -37     
+ Partials       4642       4639         -3     

[maxshuang]

https://github.com/pingcap/tiflow/runs/7666668553?check_suite_focus=true
Another case for this issue.
Seems this case becomes unstable after pr #6436

[amyangfei]

/merge

[ti-chi-bot]

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

Commit hash: b1e4733

[maxshuang]

After offline discussion with amyangfei and CharlesCheung96,
we need to investigate whether the new merged pr causes the behavior that job is dispatched to an offline executor.

[ti-chi-bot]

@amyangfei: 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.