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syscall: signal SIGURG(I/O condition) on go1.14.1, but no SIGURG signal before go 1.14 #38290

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yangwenmai opened this issue Apr 7, 2020 · 3 comments

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@yangwenmai
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@yangwenmai yangwenmai commented Apr 7, 2020

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

$ go version
1.14.1
1.13.8

Does this issue reproduce with the latest release?

Yes

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

go env Output
$ go env

GO111MODULE=""
GOARCH="amd64"
GOBIN="/Users/maiyang/develop/goworkspace/bin"
GOCACHE="/Users/maiyang/Library/Caches/go-build"
GOENV="/Users/maiyang/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/maiyang/develop/goworkspace"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/Users/maiyang/develop/go1.13.8"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/Users/maiyang/develop/go1.13.8/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
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 -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/hy/qzqhs53939lg6b93mr419lnh0000gn/T/go-build297497902=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

package main

import (
	"fmt"
	"os"
    "runtime"
	"os/signal"
	"syscall"
)

func main() {
	s := make(chan os.Signal, 1)
	signal.Notify(s)
	go func() {
		for {
		}
	}()
	for {
		switch signal := <-s; signal {
		case os.Interrupt, os.Kill, syscall.SIGABRT, syscall.SIGTERM:
			fmt.Println("stopped")
			return
			case syscall.SIGURG:
			 fmt.Println("sigurg")
			runtime.Gosched()
		default:
			fmt.Printf("unhandled signal: %v\n", signal)
		}
	}
}

What did you expect to see?

Output:

sigurg
sigurg
sigurg
sigurg
sigurg
sigurg
...

What did you see instead?

On go1.14.1 is output:

sigurg
sigurg
sigurg
sigurg
sigurg
sigurg
...

But on go1.13.8 is empty output.

Maybe we should keep the same with the old version(empty output)?

@OneOfOne
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@OneOfOne OneOfOne commented Apr 7, 2020

@andybons
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@andybons andybons commented Apr 7, 2020

Duplicate of #37942

@andybons andybons marked this as a duplicate of #37942 Apr 7, 2020
@andybons andybons closed this Apr 7, 2020
@yangwenmai
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@yangwenmai yangwenmai commented Apr 8, 2020

Thanks.

hitzhangjie added a commit to hitzhangjie/godbg that referenced this issue Aug 29, 2020
go1.14 implements non-cooperative preemption, chooses SIGURG as the signal
to notify the thread to stop goroutine.
golang/go#38290 (comment)

So, in debugger, SIGURG should be ignored.
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