Fix: optimize nodelock scalability with exponential backoff and listers

[maishivamhoo123]

What type of PR is this?
/kind feature

What this PR does / why we need it:
Optimizes node locking to handle high concurrency.

1. Implements exponential backoff in nodelock to stop retry storms.
2. Uses Informer cache instead of direct API calls in scheduler Bind() to reduce API load.

Which issue(s) this PR fixes:
Fixes #1655

[gemini-code-assist]

Summary of Changes

Hello @maishivamhoo123, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request focuses on enhancing the scalability and performance of the system by addressing potential bottlenecks in node locking and scheduler operations. By introducing exponential backoff for retries and leveraging cached data for resource lookups, the changes aim to improve resilience and reduce the load on the Kubernetes API server, particularly in high-concurrency environments.

Highlights

• Nodelock Scalability: Implemented exponential backoff in the nodelock utility to prevent retry storms and improve scalability under high concurrency.
• Scheduler Performance: Optimized the scheduler's Bind() function to use Informer caches (listers) for retrieving Pod and Node information, reducing direct API calls and API server load.

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Changelog

• pkg/scheduler/scheduler.go
  • Replaced direct kubeClient.CoreV1().Pods().Get() with s.podLister.Pods().Get() for pod retrieval.
  • Replaced direct kubeClient.CoreV1().Nodes().Get() with s.nodeLister.Get() for node retrieval.
  • Updated error messages to reflect retrieval from cache.
• pkg/scheduler/scheduler_test.go
  • Removed sync package import.
  • Refactored Test_ListNodes_Concurrent to use a done channel instead of sync.WaitGroup for goroutine synchronization.
  • Removed comments related to concurrent map iteration panic.
• pkg/util/nodelock/nodelock.go
  • Modified DefaultStrategy backoff Factor from 1.0 to 2.0.
  • Modified DefaultStrategy backoff Jitter from 0.1 to 0.5.
• pkg/util/nodelock/nodelock_test.go
  • Added context and metav1 imports.
  • Introduced TestSimulateRetryStorm to verify the exponential backoff strategy's effectiveness in spreading load and preventing excessive collisions.

Activity

• No human activity has occurred on this pull request yet.

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[gemini-code-assist]

Code Review

This pull request introduces significant optimizations to improve scalability and reduce API server load. The switch to using informer caches (podLister and nodeLister) in the Bind function is a great improvement that will reduce direct calls to the Kubernetes API. Additionally, implementing exponential backoff with increased jitter for the node lock retry strategy is a solid approach to mitigate contention and prevent retry storms under high concurrency. The changes are well-implemented and include a valuable new test to validate the effectiveness of the backoff strategy. Overall, this is a high-quality contribution that enhances the scheduler's performance and robustness.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
pkg/scheduler/scheduler.go	0.00%	4 Missing ⚠️

Flag	Coverage Δ
unittests	51.58% <0.00%> (+0.02%)	⬆️

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

Files with missing lines	Coverage Δ
pkg/util/nodelock/nodelock.go	62.87% <ø> (ø)
pkg/scheduler/scheduler.go	45.02% <0.00%> (+0.43%)	⬆️

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[maishivamhoo123]

@archlitchi and @FouoF can you please review this PR?
Thank You.

[archlitchi]

CC @FouoF @Shouren

Have you tested on your environment?

[FouoF]

/lgtm
As @shizheng163 described in #1655, this is a minimal optimization and it is lgtm

[FouoF]

/lgtm

[Shouren]

/lgtm

[hami-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: FouoF, maishivamhoo123, Shouren

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• OWNERS [FouoF,Shouren]

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