[jira] [Created] (YUNIKORN-3493) [Core] Eliminate redundant second pass and snapshot cloning in calculateVictimsByNode

["Hedger Lai (Jira)" <ji...@apache.org>]

Hedger Lai created YUNIKORN-3493:
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             Summary: [Core] Eliminate redundant second pass and snapshot cloning in calculateVictimsByNode
                 Key: YUNIKORN-3493
                 URL: https://issues.apache.org/jira/browse/YUNIKORN-3493
             Project: Apache YuniKorn
          Issue Type: Improvement
          Components: core - scheduler
            Reporter: Hedger Lai
            Assignee: Hedger Lai


h3. Problem
In {{Preemptor.calculateVictimsByNode()}}, victim selection currently runs two full passes over candidate allocations and calls {{p.duplicateQueueSnapshots()}} and {{nodeAvailable.Clone()}} twice per node:
1. In the first pass, {{head}} victims already have their allocations deducted from {{allocationsByQueueSnap}} and added to {{nodeCurrentAvailable}}, while {{tail}} victims have their queue deductions reverted.
2. Once {{nodeCurrentAvailable}} fits the ask in the first pass, the loop still computes {{SubEliminateNegative}} shortfall checks for every remaining candidate instead of directly moving the remaining slice to {{tail}}.
3. The function then resets {{nodeCurrentAvailable}} and clones {{allocationsByQueueSnap}} a second time just to re-verify {{head}} and {{tail}} from scratch.

h3. Proposed Improvement
1. Stop the first pass early once {{nodeCurrentAvailable.FitIn(p.ask.GetAllocatedResource())}} is satisfied, appending {{potentialVictims[i+1:]}} directly to {{tail}}.
2. Reuse the existing {{allocationsByQueueSnap}} from the first pass (which already reflects all {{head}} deductions) to validate and append eligible {{tail}} victims, eliminating the redundant second pass and duplicate snapshot cloning.
3. Extract {{tryRemoveVictimFromQueue}} helper to remove duplicated queue constraint checks and the {{//nolint:funlen}} directive.



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