Don't create parallel cursor if we have only one element in dataview #197
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| @@ -143,7 +143,7 @@ public override IRowCursor[] GetRowCursorSet(out IRowCursorConsolidator consolid | |||
| var inputs = Source.GetRowCursorSet(out consolidator, predicateInput, n, rand); | |||
| Contracts.AssertNonEmpty(inputs); | |||
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| if (inputs.Length == 1 && n > 1 && WantParallelCursors(predicate)) | |||
| if (inputs.Length == 1 && n > 1 && WantParallelCursors(predicate) && Source.GetRowCount() != 1) | |||
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!= 1 [](start = 101, length = 5)
<=n perhaps- no point of setting up N pipelines for <n items. The overhead is too high. #Closed
| @@ -143,7 +143,7 @@ public override IRowCursor[] GetRowCursorSet(out IRowCursorConsolidator consolid | |||
| var inputs = Source.GetRowCursorSet(out consolidator, predicateInput, n, rand); | |||
| Contracts.AssertNonEmpty(inputs); | |||
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| if (inputs.Length == 1 && n > 1 && WantParallelCursors(predicate)) | |||
| if (inputs.Length == 1 && n > 1 && WantParallelCursors(predicate) && Source.GetRowCount() != 1) | |||
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GetRowCount [](start = 88, length = 11)
However, the issue with this solution is that if user sets up a true enumerable, we will do a parallel clustering setup. At least emprirically it appears that setting up parallel cursors for scoring is 10k x slower vs not. Why we even doing this at all? The only time it will be worth doing if we are having on the order of 10k items to score. #WontFix
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We don't know size of Source in general, so nothing we can do. At least with current interfaces. I guess I can propagate parameter which would forbid usage of parallel cursor, but's it's a lot of changes.
Plus in current situation, we are forcing data to be array
In reply to: 189992635 [](ancestors = 189992635)
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Specifically that array can possibly be recycled.
Longer term we should use the row to row mappers that Yael has developed.
In reply to: 190086316 [](ancestors = 190086316,189992635)
| @@ -432,6 +432,8 @@ public override bool CanShuffle | |||
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| public override long? GetRowCount(bool lazy = true) | |||
| { | |||
| if (_data is ICollection<TRow> collection) | |||
| return collection.Count; | |||
| return null; | |||
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Interesting. Might be simpler as return (_data as ICollection<TRow>)?.Count;. #Resolved
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Thanks @Ivanidzo4ka -- this strikes me as a positive change, not the final word on this subject I'm sure but it at least partially solves the most important subcase.
…otnet#197) * Don't create parallel cursor if we have only one element in dataview * update for comments
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related to #179