fix panic when capacity plugins real capacity is nil when clone happen

[rockburning]

fix panic when clone when real capacity is nil

[volcano-sh-bot]

Welcome @rockburning!

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[gemini-code-assist]

Summary of Changes

Hello @rockburning, 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 addresses a critical panic that occurs when the realCapacity field of capacity plugins is nil during a cloning operation. The fix ensures that realCapability is always initialized to an empty resource, thereby preventing the panic and improving the stability of the capacity plugin.

Highlights

• Panic Fix: Addressed a panic condition in the capacityPlugin by initializing the realCapability field within the newQueueAttr function. Previously, this field could be nil, leading to a panic during cloning operations.

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[gemini-code-assist]

Code Review

This pull request addresses a critical panic that could occur within the capacity scheduling plugin. The panic was caused by a nil pointer dereference when cloning a queueAttr struct, specifically when the realCapability field was nil. The fix involves initializing realCapability to an empty resource within the newQueueAttr function, ensuring it is always non-nil. This change is correct and effectively prevents the panic, improving the stability of the scheduler, particularly in hierarchical queue configurations.

[JesseStutler]

What's the root cause? Can you provide more details on the issue background? Why does initializing a realCapability solve it?

[rockburning]

What's the root cause? Can you provide more details on the issue background? Why does initializing a realCapability solve it?

you can see from the picture,it will clone panic when realCapability is nil,it will access the member of the struct. type Resource struct {
MilliCPU float64
Memory float64

// ScalarResources
ScalarResources map[v1.ResourceName]float64

// MaxTaskNum is only used by predicates; it should NOT
// be accounted in other operators, e.g. Add.
MaxTaskNum int

},to avoid this, so i initialize realCapability with empty resource

[JesseStutler]

We need to confirm the triggering scenario more precisely, is it a hierarchical queue or a non-hierarchical queue scenario? Regardless of whether the hierarchical queue is enabled or not, realCapability is now assigned a value instead of nil, so we need to know the actual root cause

[rockburning]

it is a hierarchical queue ，

…

---- Replied Message ---- | From | Jesse ***@***.***> | | Date | 08/27/2025 17:07 | | To | volcano-sh/volcano ***@***.***> | | Cc | BurningRock ***@***.***>, Mention ***@***.***> | | Subject | Re: [volcano-sh/volcano] fix panic when capacity plugins real capacity is nil when clone happen (PR #4558) | JesseStutler left a comment (volcano-sh/volcano#4558) We need to confirm the triggering scenario more precisely, is it a hierarchical queue or a non-hierarchical queue scenario? Regardless of whether the hierarchical queue is enabled or not, realCapability is now assigned a value instead of nil, so we need to know the actual root cause — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you were mentioned.Message ID: ***@***.***>

[JesseStutler]

Strange thing is that:

volcano/pkg/scheduler/plugins/capacity/capacity.go

Lines 809 to 815 in b27b2a9

	realCapability := api.ExceededPart(attr.realCapability, totalGuarantee).Add(childAttr.guarantee)
	if childAttr.capability == nil {
	childAttr.capability = api.EmptyResource()
	childAttr.realCapability = realCapability
	} else {
	realCapability.MinDimensionResource(childAttr.capability, api.Infinity)
	childAttr.realCapability = realCapability

If we opened hierarchical queues, all queues' realCapability can be successfully initialized, so why still cause panic?

Which version of volcano did you use?

[rockburning]

i use the master branch， i will check it when i have free time

…

---- Replied Message ---- | From | Jesse ***@***.***> | | Date | 08/28/2025 15:28 | | To | volcano-sh/volcano ***@***.***> | | Cc | BurningRock ***@***.***>, Mention ***@***.***> | | Subject | Re: [volcano-sh/volcano] fix panic when capacity plugins real capacity is nil when clone happen (PR #4558) | JesseStutler left a comment (volcano-sh/volcano#4558) Strange thing is that: https://github.com/volcano-sh/volcano/blob/b27b2a96e0a73a4bd0f64f770cd022863a6d4b4e/pkg/scheduler/plugins/capacity/capacity.go#L809-L815 If we opened hierarchical queues, all queues' realCapability can be successfully initialized, so why still cause panic? Which version of volcano did you use? — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you were mentioned.Message ID: ***@***.***>

[hajnalmt]

This has the DCO not signed.
Let's close it as a duplicate of #4611 and merge the other one I think.