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Justin Nuß authored
In many cases the records returned by Reader.Read will only be used between calls to Read and become garbage once a new record is read. In this case, instead of allocating a new slice on each call to Read, we can reuse the last allocated slice for successive calls to avoid unnecessary allocations. This change adds a new field ReuseRecord to the Reader struct to enable this reuse. ReuseRecord is false by default to avoid breaking existing code which dependss on the current behaviour. I also added 4 new benchmarks, corresponding to the existing Read benchmarks, which set ReuseRecord to true. Benchstat on my local machine (old is ReuseRecord = false, new is ReuseRecord = true) name old time/op new time/op delta Read-8 2.75µs ± 2% 1.88µs ± 1% -31.52% (p=0.000 n=14+15) ReadWithFieldsPerRecord-8 2.75µs ± 0% 1.89µs ± 1% -31.43% (p=0.000 n=13+13) ReadWithoutFieldsPerRecord-8 2.77µs ± 1% 1.88µs ± 1% -32.06% (p=0.000 n=15+15) ReadLargeFields-8 55.4µs ± 1% 54.2µs ± 0% -2.07% (p=0.000 n=15+14) name old alloc/op new alloc/op delta Read-8 664B ± 0% 24B ± 0% -96.39% (p=0.000 n=15+15) ReadWithFieldsPerRecord-8 664B ± 0% 24B ± 0% -96.39% (p=0.000 n=15+15) ReadWithoutFieldsPerRecord-8 664B ± 0% 24B ± 0% -96.39% (p=0.000 n=15+15) ReadLargeFields-8 3.94kB ± 0% 2.98kB ± 0% -24.39% (p=0.000 n=15+15) name old allocs/op new allocs/op delta Read-8 18.0 ± 0% 8.0 ± 0% -55.56% (p=0.000 n=15+15) ReadWithFieldsPerRecord-8 18.0 ± 0% 8.0 ± 0% -55.56% (p=0.000 n=15+15) ReadWithoutFieldsPerRecord-8 18.0 ± 0% 8.0 ± 0% -55.56% (p=0.000 n=15+15) ReadLargeFields-8 24.0 ± 0% 12.0 ± 0% -50.00% (p=0.000 n=15+15) Fixes #19721 Change-Id: I79b14128bb9bb3465f53f40f93b1b528a9da6f58 Reviewed-on: https://go-review.googlesource.com/41730Reviewed-by:
Brad Fitzpatrick <bradfitz@golang.org> Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
2181653b
