7d7fd6d362
CopyBuffer allocates a 32k buffer when no buffer is available. Allocate these buffers from a sync.Pool. This removes an optimization where the copy buffer size was reduced when the source is a io.LimitedReader (including the case of CopyN) with a limit less than the default buffer size. This change could cause a program which only uses io.Copy with sources with a small limit to allocate unnecessarily large buffers. Programs which care about the transient buffer allocation can avoid this by providing their own buffer. name old time/op new time/op delta CopyNSmall-10 165ns ± 7% 117ns ± 7% -29.19% (p=0.001 n=7+7) CopyNLarge-10 7.33µs ±34% 4.07µs ± 2% -44.52% (p=0.001 n=7+7) name old alloc/op new alloc/op delta CopyNSmall-10 2.20kB ±12% 1.20kB ± 4% -45.24% (p=0.000 n=8+7) CopyNLarge-10 148kB ± 9% 81kB ± 4% -45.26% (p=0.000 n=8+7) name old allocs/op new allocs/op delta CopyNSmall-10 2.00 ± 0% 1.00 ± 0% -50.00% (p=0.000 n=8+8) CopyNLarge-10 2.00 ± 0% 1.00 ± 0% -50.00% (p=0.000 n=8+8) For #57202 Change-Id: I2292226da9ba1dc09a2543f5d74fe5da06080d49 Reviewed-on: https://go-review.googlesource.com/c/go/+/456555 TryBot-Result: Gopher Robot <gobot@golang.org> Run-TryBot: Damien Neil <dneil@google.com> Reviewed-by: Thomas Austad <thomas.austad@gmail.com> Auto-Submit: Damien Neil <dneil@google.com> Reviewed-by: Ian Lance Taylor <iant@google.com> |
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README.md
The Go Programming Language
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