This sample, based on the Object Pool Pattern, shows very clearly how the reuse of object instances can massively increase performance while reducing memory consumption.
Sample with ASP.NET Core: Object reuse with ObjectPool in ASP.NET Core
For better comparability, additional string concat were added.
BenchmarkDotNet v0.14.0, Windows 10 (10.0.19045.5131/22H2/2022Update)
AMD Ryzen 9 9950X, 1 CPU, 32 logical and 16 physical cores
.NET SDK 9.0.100
[Host] : .NET 9.0.0 (9.0.24.52809), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
.NET 7.0 : .NET 7.0.20 (7.0.2024.26716), X64 RyuJIT AVX2
.NET 8.0 : .NET 8.0.11 (8.0.1124.51707), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
.NET 9.0 : .NET 9.0.0 (9.0.24.52809), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
| Method | Runtime | Lines | Mean | StdDev | Ratio | Gen0 | Gen1 | Gen2 |
|------------ |--------- |------ |---------------:|-------------:|------:|-----------:|-----------:|-----------:|
| SB_NoPool | .NET 7.0 | 100 | 863.6 ns | 10.97 ns | 2.22 | 1.6174 | 0.1011 | - |
| SB_NoPool | .NET 8.0 | 100 | 764.9 ns | 9.05 ns | 1.96 | 1.6174 | 0.1001 | - |
| SB_NoPool | .NET 9.0 | 100 | 750.5 ns | 6.98 ns | 1.93 | 1.6174 | 0.1001 | - |
| | | | | | | | | |
| SB_Pooled | .NET 7.0 | 100 | 501.2 ns | 4.79 ns | 1.29 | 0.5922 | - | - |
| SB_Pooled | .NET 8.0 | 100 | 399.0 ns | 5.24 ns | 1.02 | 0.5927 | - | - |
| SB_Pooled | .NET 9.0 | 100 | 389.3 ns | 3.55 ns | 1.00 | 0.5927 | - | - |
| | | | | | | | | |
| ConcatShort | .NET 7.0 | 100 | 6,487.4 ns | 115.96 ns | 16.67 | 20.0729 | 0.3586 | - |
| ConcatShort | .NET 8.0 | 100 | 6,454.2 ns | 92.85 ns | 16.58 | 20.0729 | 0.4425 | - |
| ConcatShort | .NET 9.0 | 100 | 6,316.7 ns | 93.53 ns | 16.23 | 20.0729 | 0.4425 | - |
| | | | | | | | | |
| ConcatLong | .NET 7.0 | 100 | 6,405.4 ns | 73.79 ns | 16.45 | 20.0729 | 0.3586 | - |
| ConcatLong | .NET 8.0 | 100 | 6,464.1 ns | 106.38 ns | 16.61 | 20.0729 | 0.4425 | - |
| ConcatLong | .NET 9.0 | 100 | 6,298.1 ns | 85.69 ns | 16.18 | 20.0729 | 0.4425 | - |
| | | | | | | | | |
| ConcatList | .NET 7.0 | 100 | 1,094.5 ns | 7.94 ns | 2.81 | 0.5951 | - | - |
| ConcatList | .NET 8.0 | 100 | 723.2 ns | 5.26 ns | 1.86 | 0.5960 | - | - |
| ConcatList | .NET 9.0 | 100 | 656.8 ns | 7.05 ns | 1.69 | 0.5960 | - | - |
| | | | | | | | | |
|-------------|----------|-------|----------------|--------------|-------|------------|------------|------------|
| | | | | | | | | |
| SB_NoPool | .NET 7.0 | 500 | 66,533.0 ns | 1,439.03 ns | 1.25 | 76.9043 | 76.9043 | 76.9043 |
| SB_NoPool | .NET 9.0 | 500 | 61,729.7 ns | 846.96 ns | 1.16 | 76.9043 | 76.9043 | 76.9043 |
| SB_NoPool | .NET 8.0 | 500 | 64,277.6 ns | 1,435.26 ns | 1.20 | 76.9043 | 76.9043 | 76.9043 |
| | | | | | | | | |
| SB_Pooled | .NET 7.0 | 500 | 56,434.1 ns | 1,616.89 ns | 1.06 | 76.9043 | 76.9043 | 76.9043 |
| SB_Pooled | .NET 8.0 | 500 | 54,723.3 ns | 1,105.22 ns | 1.03 | 76.9043 | 76.9043 | 76.9043 |
| SB_Pooled | .NET 9.0 | 500 | 53,360.1 ns | 421.15 ns | 1.00 | 76.9043 | 76.9043 | 76.9043 |
| | | | | | | | | |
| ConcatShort | .NET 7.0 | 500 | 1,142,275.1 ns | 25,572.21 ns | 21.41 | 10332.0313 | 10332.0313 | 10332.0313 |
| ConcatShort | .NET 8.0 | 500 | 1,028,992.2 ns | 11,862.41 ns | 19.29 | 10332.0313 | 10332.0313 | 10332.0313 |
| ConcatShort | .NET 9.0 | 500 | 1,019,582.2 ns | 14,081.10 ns | 19.11 | 10332.0313 | 10332.0313 | 10332.0313 |
| | | | | | | | | |
| ConcatLong | .NET 7.0 | 500 | 1,166,315.0 ns | 29,884.12 ns | 21.86 | 10332.0313 | 10332.0313 | 10332.0313 |
| ConcatLong | .NET 8.0 | 500 | 1,027,497.5 ns | 16,457.49 ns | 19.26 | 10332.0313 | 10332.0313 | 10332.0313 |
| ConcatLong | .NET 9.0 | 500 | 1,016,028.4 ns | 14,626.49 ns | 19.04 | 10332.0313 | 10332.0313 | 10332.0313 |
| | | | | | | | | |
| ConcatList | .NET 7.0 | 500 | 64,373.8 ns | 1,292.36 ns | 1.21 | 76.9043 | 76.9043 | 76.9043 |
| ConcatList | .NET 8.0 | 500 | 60,955.1 ns | 624.88 ns | 1.14 | 76.9043 | 76.9043 | 76.9043 |
| ConcatList | .NET 9.0 | 500 | 60,583.6 ns | 847.82 ns | 1.14 | 76.9043 | 76.9043 | 76.9043 |- 🔋 StringBuilder itself has the best performance and lowest allocations
- 🐏 No additional memory allocations (only if strings are huge) for the string builder instance
- 🏃♀️ The larger the strings, the clearer the performance advantage for pooling.
- 🏎️ Pooling is a performance boost
- 🚀 The ratio clearly shows: without pool up always slower and huge allocations (incl. expensive Gen2) for this sample
- 🎒 ConcatList uses string.concat(IEnumable), which uses the internal type ValueStringBuilder under the hood, why the allocation is almost the same
- This sample is about pooling, not about string operations in general.
- Pooling is great and powerful
- For strings, there are also more performant solutions with unsafe code.
- If you know the total string size, use string.create to benefit from pre-allocations.
dotnet run -c Release --framework net9.0- 2023/11 - Add .NET 8
- 2024/11 - Add .NET 9