Improve perf of ActivatorUtilities.CreateInstance() by avoiding an alloc per ctor

[steveharter]

The current implementation allocs a struct for each ctor; the struct was changed to be ref struct \ byref-like type

Found when working on #99175.

Affects the CreateInstance* benchmarks; 3x-4x faster for existing benchmarks (which typically have 3 ctors);

| Method                                 | Job        | Toolchain              | Mean      | Error    | StdDev   | Median    | Min       | Max       | Ratio | RatioSD | Gen0   | Allocated | Alloc Ratio |
|--------------------------------------- |----------- |----------------------- |----------:|---------:|---------:|----------:|----------:|----------:|------:|--------:|-------:|----------:|------------:|
| CreateInstance_0                       | Job-IPPVWX | \DI_AFTER\corerun.exe  |  32.73 ns | 0.158 ns | 0.140 ns |  32.72 ns |  32.47 ns |  33.00 ns |  1.00 |    0.00 | 0.0046 |      48 B |        1.00 |
| CreateInstance_0                       | Job-LQPVEO | \DI_BEFORE\corerun.exe | 112.61 ns | 0.679 ns | 0.567 ns | 112.61 ns | 111.73 ns | 113.76 ns |  3.44 |    0.02 | 0.0074 |      80 B |        1.67 |
|                                        |            |                        |           |          |          |           |           |           |       |         |        |           |
| CreateInstance_1                       | Job-IPPVWX | \DI_AFTER\corerun.exe  |  82.42 ns | 0.869 ns | 0.813 ns |  82.21 ns |  81.33 ns |  84.40 ns |  1.00 |    0.00 | 0.0112 |     120 B |        1.00 |
| CreateInstance_1                       | Job-LQPVEO | \DI_BEFORE\corerun.exe | 350.47 ns | 3.106 ns | 2.905 ns | 351.30 ns | 344.55 ns | 354.73 ns |  4.25 |    0.05 | 0.0239 |     264 B |        2.20 |
|                                        |            |                        |           |          |          |           |           |           |       |         |        |           |
| CreateInstance_2                       | Job-IPPVWX | \DI_AFTER\corerun.exe  | 109.00 ns | 1.101 ns | 1.030 ns | 108.67 ns | 107.70 ns | 111.20 ns |  1.00 |    0.00 | 0.0160 |     168 B |        1.00 |
| CreateInstance_2                       | Job-LQPVEO | \DI_BEFORE\corerun.exe | 471.02 ns | 2.956 ns | 2.469 ns | 470.22 ns | 467.44 ns | 476.03 ns |  4.33 |    0.04 | 0.0342 |     360 B |        2.14 |
|                                        |            |                        |           |          |          |           |           |           |       |         |        |           |
| CreateInstance_3                       | Job-IPPVWX | \DI_AFTER\corerun.exe  |  71.83 ns | 0.722 ns | 0.563 ns |  71.81 ns |  70.54 ns |  72.81 ns |  1.00 |    0.00 | 0.0082 |      88 B |        1.00 |
| CreateInstance_3                       | Job-LQPVEO | \DI_BEFORE\corerun.exe | 182.74 ns | 1.460 ns | 1.294 ns | 182.96 ns | 180.28 ns | 184.77 ns |  2.54 |    0.03 | 0.0156 |     168 B |        1.91 |
|                                        |            |                        |           |          |          |           |           |           |       |         |        |           |
| CreateInstance_4                       | Job-IPPVWX | \DI_AFTER\corerun.exe  | 138.91 ns | 1.209 ns | 1.072 ns | 138.69 ns | 137.40 ns | 140.92 ns |  1.00 |    0.00 | 0.0186 |     200 B |        1.00 |
| CreateInstance_4                       | Job-LQPVEO | \DI_BEFORE\corerun.exe | 505.69 ns | 1.958 ns | 1.529 ns | 505.54 ns | 503.81 ns | 507.96 ns |  3.64 |    0.03 | 0.0386 |     408 B |        2.04 |
|                                        |            |                        |           |          |          |           |           |           |       |         |        |           |
| CreateInstance_5                       | Job-IPPVWX | \DI_AFTER\corerun.exe  | 170.57 ns | 1.498 ns | 1.401 ns | 169.98 ns | 169.04 ns | 173.50 ns |  1.00 |    0.00 | 0.0204 |     216 B |        1.00 |
| CreateInstance_5                       | Job-LQPVEO | \DI_BEFORE\corerun.exe | 538.60 ns | 4.917 ns | 4.600 ns | 538.12 ns | 532.02 ns | 546.83 ns |  3.16 |    0.04 | 0.0405 |     432 B |        2.00 |

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Issue Details

---

The current implementation allocs a struct for each ctor; the struct was changed to be ref struct \ byref-like type

Affects the CreateInstance* benchmarks; 3x-4x faster for existing benchmarks (which typically have 3 ctors);

| Method                                 | Job        | Toolchain              | Mean      | Error    | StdDev   | Median    | Min       | Max       | Ratio | RatioSD | Gen0   | Allocated | Alloc Ratio |
|--------------------------------------- |----------- |----------------------- |----------:|---------:|---------:|----------:|----------:|----------:|------:|--------:|-------:|----------:|------------:|
| CreateInstance_0                       | Job-IPPVWX | \DI_AFTER\corerun.exe  |  32.73 ns | 0.158 ns | 0.140 ns |  32.72 ns |  32.47 ns |  33.00 ns |  1.00 |    0.00 | 0.0046 |      48 B |        1.00 |
| CreateInstance_0                       | Job-LQPVEO | \DI_BEFORE\corerun.exe | 112.61 ns | 0.679 ns | 0.567 ns | 112.61 ns | 111.73 ns | 113.76 ns |  3.44 |    0.02 | 0.0074 |      80 B |        1.67 |
|                                        |            |                        |           |          |          |           |           |           |       |         |        |           |
| CreateInstance_1                       | Job-IPPVWX | \DI_AFTER\corerun.exe  |  82.42 ns | 0.869 ns | 0.813 ns |  82.21 ns |  81.33 ns |  84.40 ns |  1.00 |    0.00 | 0.0112 |     120 B |        1.00 |
| CreateInstance_1                       | Job-LQPVEO | \DI_BEFORE\corerun.exe | 350.47 ns | 3.106 ns | 2.905 ns | 351.30 ns | 344.55 ns | 354.73 ns |  4.25 |    0.05 | 0.0239 |     264 B |        2.20 |
|                                        |            |                        |           |          |          |           |           |           |       |         |        |           |
| CreateInstance_2                       | Job-IPPVWX | \DI_AFTER\corerun.exe  | 109.00 ns | 1.101 ns | 1.030 ns | 108.67 ns | 107.70 ns | 111.20 ns |  1.00 |    0.00 | 0.0160 |     168 B |        1.00 |
| CreateInstance_2                       | Job-LQPVEO | \DI_BEFORE\corerun.exe | 471.02 ns | 2.956 ns | 2.469 ns | 470.22 ns | 467.44 ns | 476.03 ns |  4.33 |    0.04 | 0.0342 |     360 B |        2.14 |
|                                        |            |                        |           |          |          |           |           |           |       |         |        |           |
| CreateInstance_3                       | Job-IPPVWX | \DI_AFTER\corerun.exe  |  71.83 ns | 0.722 ns | 0.563 ns |  71.81 ns |  70.54 ns |  72.81 ns |  1.00 |    0.00 | 0.0082 |      88 B |        1.00 |
| CreateInstance_3                       | Job-LQPVEO | \DI_BEFORE\corerun.exe | 182.74 ns | 1.460 ns | 1.294 ns | 182.96 ns | 180.28 ns | 184.77 ns |  2.54 |    0.03 | 0.0156 |     168 B |        1.91 |
|                                        |            |                        |           |          |          |           |           |           |       |         |        |           |
| CreateInstance_4                       | Job-IPPVWX | \DI_AFTER\corerun.exe  | 138.91 ns | 1.209 ns | 1.072 ns | 138.69 ns | 137.40 ns | 140.92 ns |  1.00 |    0.00 | 0.0186 |     200 B |        1.00 |
| CreateInstance_4                       | Job-LQPVEO | \DI_BEFORE\corerun.exe | 505.69 ns | 1.958 ns | 1.529 ns | 505.54 ns | 503.81 ns | 507.96 ns |  3.64 |    0.03 | 0.0386 |     408 B |        2.04 |
|                                        |            |                        |           |          |          |           |           |           |       |         |        |           |
| CreateInstance_5                       | Job-IPPVWX | \DI_AFTER\corerun.exe  | 170.57 ns | 1.498 ns | 1.401 ns | 169.98 ns | 169.04 ns | 173.50 ns |  1.00 |    0.00 | 0.0204 |     216 B |        1.00 |
| CreateInstance_5                       | Job-LQPVEO | \DI_BEFORE\corerun.exe | 538.60 ns | 4.917 ns | 4.600 ns | 538.12 ns | 532.02 ns | 546.83 ns |  3.16 |    0.04 | 0.0405 |     432 B |        2.00 |

Author:	steveharter
Assignees:	steveharter
Labels:	tenet-performance, area-Extensions-DependencyInjection
Milestone:	9.0.0

[jkotas]

How does changing the struct to ref struct avoids the allocation?

[steveharter]

How does changing the struct to ref struct avoids the allocation?

Yes - sorry. This was premature and got conflated with a previous commit that cached the ConstructorInfoExs in a static.