MVC: Minimize memory consumption by routing data structures

[AlexanderKot]

Is there an existing issue for this?

• I have searched the existing issues

Is your feature request related to a problem? Please describe the problem.

After startup our application consume significant amount of memory related to MVC routing.
It currently uses .net8.
There are 700+controllers with ~60 method per controller.
Most of controllers inherited from base generic controllers hierarchy, many controllers final type generated at runtime by closing opened generic base controller.
As result at runtime there are many controllers with same method names and parameter names.

After startup we can see next memory consumers:

There are many duplicated strings in memory (~8% of all allocated objects), where strings referenced by MVC.routing take 1st, 3d, 5th, 9th ..... places

Some examples with string referenced by routing structures directly.

Parameter name:

Value	Wasted	Count
cancellationToken	484,5 KB	14593

Value	Wasted	Count
filterId	230,83 KB	14774
viewId	173,14 KB	14776

Http verb name:

Value	Wasted	Count
POST	120,36 KB	15407
GET	67,28 KB	11483

Controller action name:

Value	Wasted	Count
GetLayoutsPanelForPropertyGridAsync	50,11 KB	734

Also sparse arrays related to MVC routing are in TOP of memory killers.

Type	Wasted	Count
System.Collections.Concurrent.ConcurrentDictionary+VolatileNode<System.Type, System.Object[]>[]	11,83 MB	43118

99.9% of theses Dictionaries contains 1 element

Type	Wasted	Count
System.Collections.Generic.Dictionary+Entry<System.String[], System.Collections.Generic.List<Microsoft.AspNetCore.Http.Endpoint>>[]	1,55 MB	2

Type	Wasted	Count
Microsoft.AspNetCore.Http.Endpoint[]	1,11 MB	41485

Most of lists contains 1 element from 4 allocated by default

Describe the solution you'd like

Some string.Intern() when assigning string in routing data structures like ParameterDescriptor.Name and so on.
Some finalizing of routing initialization where TrimExcess will be called on routing collections.
Probably some nonstandard initial capacity for some routing collections.

Additional context

No response

[davidfowl]

Are you basically code generating controllers? Or are some of these hand rolled?

[AlexanderKot]

No code generation at all.
Big inheritance hierarchy instead.

Controller
^
BaseController : Controller
^
BaseGeneriController1<T1, T2> : BaseController
^
BaseGeneriControllerX<T1, T2.......1>: BaseGeneriControllerX-1<T1, T2........>
^
SpecificProblemDomainController : BaseGeneriControllerX<T1Specific, T2Specific........>

some Specific controllers types not declared directly, but register in DI (Castle Windsor)
Component.For<>() ......ImpementedBy<BaseGeneriControllerX<T1Specific, T2Specific........>>

Currently there are
486 Controllers with 42847 Actions

Also dynamic routing used in app, during its configuration all that can be intern'ed and TrimExcess'ed done.

[AlexanderKot]

During dynamic routing our code creates ParameterModel and assign ParameterName.
It do it for "cancellationToken" and all other params.
I am 100% sure that on this assignment string is interned, even try to assign const value in this case.
As far as I see in source, ParameterModel ParameterName then assigned to ControllerParameterDescriptor.Name without any string manipulation. So all these properties must reference same string instance.

Can it be bug\feature of VS memory snapshot explorer?
Can it display wrong "Path to root" and duplicate string really referenced
not by ControllerParameterDescriptor.Name
but by ControllerParameterDescriptor.ParameterInfo.NameImpl?