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x/sync/semaphore: newWeighted why n is int64 #27363

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Sherlock-Holo opened this issue Aug 30, 2018 · 3 comments
Closed

x/sync/semaphore: newWeighted why n is int64 #27363

Sherlock-Holo opened this issue Aug 30, 2018 · 3 comments
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FrozenDueToAge NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one.
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Unreleased

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@Sherlock-Holo
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Please answer these questions before submitting your issue. Thanks!
https://github.com/golang/sync/blob/master/semaphore/semaphore.go#L25

What version of Go are you using (go version)?

1.10.4

Does this issue reproduce with the latest release?

yes

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN=""
GOCACHE="/home/sherlock/.cache/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/sherlock/go"
GORACE=""
GOROOT="/usr/lib/go"
GOTMPDIR=""
GOTOOLDIR="/usr/lib/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build083961696=/tmp/go-build -gno-record-gcc-switches"

What did you do?

use semaphore.NewWeighted

What did you expect to see?

n should be uint64, because uint64 is large enough

What did you see instead?

n is int64
@gopherbot gopherbot added this to the Unreleased milestone Aug 30, 2018
@FiloSottile FiloSottile added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Aug 30, 2018
@FiloSottile
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I imagine the advantages of switching to uint64 are not worth breaking the API compatibility, but @jba might have more info on why.

@Sherlock-Holo
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I discussed it with my friends, we suppose we almost won't use a number larger than maxint64. however uint64 can smaller than 0 and wet won't make n smaller than 0 so it won't panic

@ianlancetaylor
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In general numbers should be signed unless it is important that they be unsigned. All computer integers have strange behavior at some points. Signed integers have strange behavior at very large absolute values. Unsigned integers have strange behavior at zero. Zero is much more common in real life, so on average we minimize surprises by using signed integers.

@golang golang locked and limited conversation to collaborators Aug 31, 2019
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@FiloSottile @ianlancetaylor @gopherbot @Sherlock-Holo