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base repository:golang/sync

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base:v0.6.0

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head repository:golang/sync

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compare:v0.7.0

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Commits on Mar 4, 2024

semaphore: cancel acquisition with a done context

When acquiring from a semaphore could proceed without contention, theprevious behavior was to always do so, even when the provided contextwas done. This was the documented behavior, but it could lead toconfusion. It isn't much more expensive to check the context error, socancel acquisition if it's done.Fixesgolang/go#63615.goos: linuxgoarch: amd64pkg: golang.org/x/sync/semaphorecpu: 12th Gen Intel(R) Core(TM) i5-1235U                                        │  old.bench  │             new.bench              │                                        │   sec/op    │   sec/op     vs base               │AcquireSeq/Weighted-acquire-1-1-1-12      26.45n ± 2%   27.25n ± 3%  +3.04% (p=0.001 n=20)AcquireSeq/Weighted-acquire-2-1-1-12      26.96n ± 1%   27.12n ± 1%       ~ (p=0.104 n=20)AcquireSeq/Weighted-acquire-16-1-1-12     26.07n ± 3%   27.48n ± 1%  +5.45% (p=0.000 n=20)AcquireSeq/Weighted-acquire-128-1-1-12    26.19n ± 2%   27.24n ± 1%  +4.01% (p=0.000 n=20)AcquireSeq/Weighted-acquire-2-2-1-12      25.61n ± 1%   25.99n ± 2%       ~ (p=0.066 n=20)AcquireSeq/Weighted-acquire-16-2-8-12     209.6n ± 2%   211.0n ± 3%       ~ (p=0.280 n=20)AcquireSeq/Weighted-acquire-128-2-64-12   1.669µ ± 1%   1.721µ ± 2%  +3.09% (p=0.000 n=20)AcquireSeq/Weighted-acquire-2-1-2-12      51.08n ± 1%   53.03n ± 2%  +3.82% (p=0.000 n=20)AcquireSeq/Weighted-acquire-16-8-2-12     52.48n ± 2%   53.66n ± 2%  +2.26% (p=0.028 n=20)AcquireSeq/Weighted-acquire-128-64-2-12   52.27n ± 1%   53.71n ± 2%  +2.75% (p=0.000 n=20)geomean                                   60.06n        61.69n       +2.71%Change-Id: I0ae1a0bb6c027461ac1a9ee71c51efd8427ab308Reviewed-on:https://go-review.googlesource.com/c/sync/+/536275Auto-Submit: Bryan Mills <bcmills@google.com>Reviewed-by: Bryan Mills <bcmills@google.com>Reviewed-by: Michael Knyszek <mknyszek@google.com>LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>