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I am trying to create a console application which hangs up in a way that pressing CTRL + BREAK or sending a SIGTERM signal to the process doesn't terminate it [i.e. it keeps on hanging, without closing]. I want to test that it keeps on going with the following Java code:

public static void main(String[] args) throws IOException {
//Replace APPLICATION PATH HERE with path towards the executable file
Process process = Runtime.getRuntime().exec("APPLICATION PATH HERE");
// this should kill the process
process.destroy();

// if the process is alive, exitValue() will throw exception
try {
  process.exitValue();
  // the process is dead - hasn't survived kill
  System.out.println("WRONG: process died");
} catch (IllegalThreadStateException e) {
  // the process is still running
  // the process is not dead and survived destroy()
  System.out.println("OK: process hanged");
}
}

So far, I have managed to find the following information: How Can I Make A Command Prompt Hang? , though it doesn't stop SIGTERM, just SIGINT. I have also tried using Shutdown Hooks in a java -jar executable file, which also give me control over SIGINT,but not over SIGTERM. I want the program to keep running when given SIGTERM,so that I test the destroy function. I have also written a program in Go which does a similar thing,with the exception that it registers CTRL+ BREAK as an interrupt,for some reason[I am not sure why, but it still doesn't handle SIGTERM signals from the java code]:

package main

import "fmt"
import "os"
import "os/signal"
import "syscall"
func main() {
sigs := make(chan os.Signal, 1)
done := make(chan bool, 1)
signal.Notify(sigs, syscall.SIGTERM, syscall.SIGINT)

go func() {
    sig := <-sigs
    fmt.Println("TEST!!")
    fmt.Println(sig)
    done <- true
}()
fmt.Println("awaiting signal")
<-done
sigs2 := make(chan os.Signal, 1)
done2 := make(chan bool, 1)
signal.Notify(sigs2, syscall.SIGTERM, syscall.SIGINT)
go func() {
    sig2 := <-sigs2
    fmt.Println("TEST!!")
    fmt.Println(sig2)
    done2 <- true
}()
fmt.Println("awaiting signal 2")
<-done2
}

NOTE: I still want to be able to close the application with a SIGKILL signal, or the red X in the window :) Thank you for any ideas :)

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Velitchko Valkov
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1 Answers1

1

From the Java API documentation (emphasis mine):

public abstract void destroy()

Kills the subprocess. The subprocess represented by this Process object is forcibly terminated.

In Windows terms, that means it terminates the process - the equivalent of SIGKILL. There is no way for a process to detect, prevent, or postpone termination.

Note that Windows does not have anything equivalent to SIGTERM. For GUI applications, the recommended procedure is documented in KB178893.

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Harry Johnston
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