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e79b57d6c4
By lazily starting the signal watch loop only on Notify, we are able to have deadlock detection even when "os/signal" is imported. Thanks to Ian Lance Taylor for the solution and discussion. With this change in, fix a runtime gorountine count test that assumed that os/signal.init would unconditionally start the signal watching goroutine, but alas no more. Fixes #21576. Change-Id: I6eecf82a887f59f2ec8897f1bcd67ca311ca42ff Reviewed-on: https://go-review.googlesource.com/c/go/+/101036 Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
61 lines
1.1 KiB
Go
61 lines
1.1 KiB
Go
// +build !nacl,!js
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// run
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// Copyright 2019 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//
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// Ensure that deadlock detection can still
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// run even with an import of "_ os/signal".
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package main
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import (
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"bytes"
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"context"
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"io/ioutil"
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"log"
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"os"
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"os/exec"
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"path/filepath"
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"time"
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)
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const prog = `
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package main
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import _ "os/signal"
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func main() {
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c := make(chan int)
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c <- 1
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}
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`
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func main() {
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dir, err := ioutil.TempDir("", "21576")
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if err != nil {
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log.Fatal(err)
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}
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defer os.RemoveAll(dir)
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file := filepath.Join(dir, "main.go")
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if err := ioutil.WriteFile(file, []byte(prog), 0655); err != nil {
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log.Fatalf("Write error %v", err)
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}
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ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
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defer cancel()
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cmd := exec.CommandContext(ctx, "go", "run", file)
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output, err := cmd.CombinedOutput()
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if err == nil {
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log.Fatalf("Passed, expected an error")
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}
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want := []byte("fatal error: all goroutines are asleep - deadlock!")
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if !bytes.Contains(output, want) {
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log.Fatalf("Unmatched error message %q:\nin\n%s", want, output)
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}
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}
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