CODEWITHSUNDEEP
gosignals
Mike DiBaggio
Mike DiBaggio

Reputation: 143

Signal other than SIGKILL not terminating process on Windows

I am launching a simple Java application through Go, with the goal of proving that Go can send a signal like SIGQUIT or SIGTERM, and the Java can catch that and handle it appropriately (i.e. shutdown gracefully). When I run the Java program on the command line and send it a CTRL+C, the Java program correctly catches the signal.

However, when I launch the Java program through Go and attempt to send the process a signal, the Java process is neither terminated nor does it handle the signal. The only one that works is SIGKILL, which of course is not caught, and simply kills the process.

Here are the relevant parts of my Go code:

Start:

startChan := make(chan bool)
go func(startChan chan<- bool) {
    a.Cmd = exec.Command("java", "-jar", "C:\\Code\\sigterm\\TestApp.jar")
    a.Cmd.Stdout = os.Stdout
    a.Cmd.Stderr = os.Stderr

    launchErr := a.Cmd.Start()
    if launchErr != nil {
        fmt.Println("Unable to start app:" + launchErr.Error())
    }
    startChan <- true
}(startChan)

Stop:

func (a *App) Stop(timeout time.Duration) {
  a.Cmd.Process.Signal(syscall.SIGQUIT) //Does not work
  a.Cmd.Process.Signal(syscall.SIGTERM) //Does not work
  a.Cmd.Process.Signal(syscall.SIGKILL) //Works
}

This is on Windows, by the way. I tried it by launching another program (notepad) and got the same results; that is, only SIGKILL worked. I have confirmed that Go is getting the correct PID and so forth, so the signal should be going to the right place.

Any ideas about how I can get this to work?

Upvotes: 3

Views: 2993

Answers (2)

Constantin Konstantinidis
Constantin Konstantinidis

Reputation: 1515

syscall package is tailored to the OS (https://golang.org/pkg/syscall/#pkg-overview). Although interrupt is not implemented on Windows, signaling is usable.

There is an example in the signal package itself for Windows. An interactive version (go run) is available here.

Upvotes: 2

eugenioy
eugenioy

Reputation: 12383

This does not seem to be supported as stated in the documentation:

https://godoc.org/os#Process.Signal

Sending Interrupt on Windows is not implemented.

Also, see this issue discussion to get more context on why it could not be done:

https://github.com/golang/go/issues/6720

Upvotes: 5

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