Optimize ancestor queue resource updates using delta propagation in capacity plugin

[kingeasternsun]

What type of PR is this?

/kind improvement

What this PR does / why we need it:

This PR optimizes the resource update mechanism for ancestor queues in hierarchical queue structures within the capacity plugin.

Optimization Details:

• Instead of recalculating all ancestor queue resources from scratch, this implementation calculates the resource deltas (differences) once for each job update
• The deltas are then efficiently propagated to all ancestor queues in the hierarchy
• This approach reduces computational overhead, especially in deep hierarchical queue structures with multiple ancestors

Performance Benefits:

• Reduces redundant calculations when updating ancestor queue resources
• Improves scheduler performance when dealing with hierarchical queues
• Scales better with deeper queue hierarchies

The optimization applies to four resource metrics:

• allocated: Resources currently allocated to pods
• request: Total resources requested
• inqueue: Resources waiting in queue
• elastic: Elastic resources available

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

• The logic preserves the same behavior as before, only optimizing the calculation method
• Old values are cloned at the beginning (lines 544-547) to calculate accurate deltas
• The delta propagation loop (lines 581-587) efficiently updates all ancestors

Does this PR introduce a user-facing change?

NONE

[volcano-sh-bot]

@kingeasternsun: The label(s) kind/improvement cannot be applied, because the repository doesn't have them.

Details

In response to this:

What type of PR is this?

/kind improvement

What this PR does / why we need it:

This PR optimizes the resource update mechanism for ancestor queues in hierarchical queue structures within the capacity plugin.

Optimization Details:

• Instead of recalculating all ancestor queue resources from scratch, this implementation calculates the resource deltas (differences) once for each job update
• The deltas are then efficiently propagated to all ancestor queues in the hierarchy
• This approach reduces computational overhead, especially in deep hierarchical queue structures with multiple ancestors

Performance Benefits:

• Reduces redundant calculations when updating ancestor queue resources
• Improves scheduler performance when dealing with hierarchical queues
• Scales better with deeper queue hierarchies

The optimization applies to four resource metrics:

• allocated: Resources currently allocated to pods
• request: Total resources requested
• inqueue: Resources waiting in queue
• elastic: Elastic resources available

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

• The logic preserves the same behavior as before, only optimizing the calculation method
• Old values are cloned at the beginning (lines 544-547) to calculate accurate deltas
• The delta propagation loop (lines 581-587) efficiently updates all ancestors

Does this PR introduce a user-facing change?

NONE

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[gemini-code-assist]

Summary of Changes

Hello @kingeasternsun, 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 aims to enhance the performance of the scheduler's capacity plugin by optimizing how resource updates are handled for hierarchical queues. By implementing a delta propagation mechanism, the system avoids costly full recalculations of ancestor queue resources, leading to more efficient updates and improved scalability, particularly in complex queue hierarchies. This change is designed to maintain existing functional behavior while significantly boosting computational efficiency.

Highlights

• Performance Optimization: The pull request introduces an optimization to the resource update mechanism for ancestor queues within the capacity plugin, specifically for hierarchical queue structures.
• Delta Propagation: Instead of recalculating all ancestor queue resources from scratch, the system now calculates resource deltas (differences) once per job update and propagates these deltas efficiently to all ancestor queues.
• Reduced Overhead: This approach significantly reduces computational overhead, especially in deep hierarchical queue structures, by avoiding redundant calculations.
• Affected Metrics: The optimization applies to four key resource metrics: 'allocated', 'request', 'inqueue', and 'elastic'.
• Behavior Preservation: The core logic and behavior remain unchanged; only the method of calculation has been optimized for efficiency.

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[gemini-code-assist]

Code Review

This pull request introduces a valid optimization to the capacity plugin by pre-calculating resource deltas for ancestor queues. This change effectively reduces redundant computations within the loop, improving performance, especially in deep hierarchical queue structures. The implementation is correct and follows the intended logic. However, there's a subtle issue with the re-use of delta variables which could lead to bugs if the Add method's contract changes in the future. I've added a comment with a suggestion to make the code more robust against such changes.

[hajnalmt]

/lgtm
nice improvement

[hajnalmt]

/cc @JesseStutler

[JesseStutler]

/approve

[volcano-sh-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JesseStutler

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Details

Needs approval from an approver in each of these files:

• pkg/scheduler/plugins/OWNERS [JesseStutler]

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