feat: when the cluster resources change, reschedule the resource templates

[chaunceyjiang]

Signed-off-by: chaunceyjiang [email protected]
What type of PR is this?
/kind feature

What this PR does / why we need it:
when the cluster resources change, reschedule the resource templates
Which issue(s) this PR fixes:
Fixes #4434

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

`karmada-scheduler`: when the cluster resources change, reschedule the resource templates

[codecov-commenter]

Codecov Report

Attention: 58 lines in your changes are missing coverage. Please review.

Comparison is base (c6b2ada) 51.89% compared to head (af21f85) 51.75%.
Report is 29 commits behind head on master.

Files	Patch %	Lines
pkg/scheduler/event_handler.go	0.00%	39 Missing ⚠️
pkg/scheduler/scheduler.go	26.31%	14 Missing ⚠️
pkg/util/binding.go	0.00%	5 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4456      +/-   ##
==========================================
- Coverage   51.89%   51.75%   -0.14%     
==========================================
  Files         243      243              
  Lines       24164    24243      +79     
==========================================
+ Hits        12539    12547       +8     
- Misses      10944    11014      +70     
- Partials      681      682       +1     

Flag	Coverage Δ
unittests	51.75% <7.93%> (-0.14%)	⬇️

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[chaunceyjiang]

@XiShanYongYe-Chang PTAL.

[XiShanYongYe-Chang]

/assign

[XiShanYongYe-Chang]

Thanks a lot~

[XiShanYongYe-Chang]

Overall, LGTM, some little suggestion.

[karmada-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[XiShanYongYe-Chang]

/lgtm
/cc @RainbowMango

[XiShanYongYe-Chang]

/cc @chaosi-zju

[karmada-bot]

New changes are detected. LGTM label has been removed.

[chaunceyjiang]

/cc @RainbowMango PTAL.

[chaosi-zju]

/lgtm thanks a lot

[RainbowMango]

/assign

[RainbowMango]

My concern is that this will make the scheduler very sensitive because the cluster's resources will be updated frequently, when there are multiple clusters, it will put a lot of pressure on the scheduler.

What I've been thinking:

1. Is it reasonable for the scheduler to give up on scheduling a resource if it can not find a feasible cluster? Should the scheduler retry these tasks? such as by introducing a retry queue?
2. Karmada needs a capability that allows users to trigger rescheduling. There are many scenarios where rescheduling is required, cluster resource change is just one small case.