Improve the performance of ImmutableList.Contains by shortspider · Pull Request #40540 · dotnet/corefx (original) (raw)
@AArnott @stephentoub
So I redid the enumerator to use the index and I don't see a real improvement. Here is without my changes:
| Type | Method | Size | Mean | Error | StdDev |
|---|---|---|---|---|---|
| IterateForEach{Int32} | ImmutableList | 512 | 12.678 us | 0.3188 us | 0.3544 us |
| IterateForEach{String} | ImmutableList | 512 | 35.445 us | 1.4779 us | 1.5177 us |
And then with the indexer implementation:
| Type | Method | Size | Mean | Error | StdDev |
|---|---|---|---|---|---|
| IterateForEach{Int32} | ImmutableList | 512 | 17.388 us | 0.0719 us | 0.0561 us |
| IterateForEach{String} | ImmutableList | 512 | 29.857 us | 3.7395 us | 4.3064 us |
Switching Contains back to use IndexOf (and the Enumerator directly) here are the results (without my changes then with indexer enumerator):
| Type | Method | Size | Mean | Error | StdDev |
|---|---|---|---|---|---|
| ContainsFalse{Int32} | ImmutableList | 512 | 8,273.21 us | 743.876 us | 856.648 us |
| ContainsFalse{String} | ImmutableList | 512 | 23,145.14 us | 3,396.777 us | 3,775.509 us |
| ContainsTrue{Int32} | ImmutableList | 512 | 3,997.04 us | 327.578 us | 377.239 us |
| ContainsTrue{String} | ImmutableList | 512 | 10,036.07 us | 29.512 us | 24.644 us |
| Type | Method | Size | Mean | Error | StdDev |
|---|---|---|---|---|---|
| ContainsFalse{Int32} | ImmutableList | 512 | 10,064.98 us | 62.073 us | 55.026 us |
| ContainsFalse{String} | ImmutableList | 512 | 13,986.43 us | 38.286 us | 35.813 us |
| ContainsTrue{Int32} | ImmutableList | 512 | 4,665.12 us | 421.096 us | 468.047 us |
| ContainsTrue{String} | ImmutableList | 512 | 7,144.50 us | 8.922 us | 7.909 us |
I don't honestly know what to make of this data, with a pure indexer implementation the enumerator for ints seems to take a performance hit while for strings it performs better.
None of this matters for the Contains case but it's interesting.