Main.java revision 0c2dc522d0e120f346cf0a40c8cf0c93346131c2 
1import java.util.Map;
2
3public class Main {
4    static public void main(String[] args) throws Exception {
5        checkManager();
6        for (int i = 1; i <= 2; i++) {
7            System.out.println("\nspawning child #" + i);
8            child();
9            Thread.sleep(2000);
10            checkManager();
11        }
12        System.out.println("\ndone!");
13    }
14
15    static private void child() throws Exception {
16        System.out.println("spawning child");
17        ProcessBuilder pb = new ProcessBuilder("sleep", "5");
18        Process proc = pb.start();
19        Thread.sleep(1000);
20        checkManager();
21        proc.waitFor();
22        System.out.println("child died");
23    }
24
25    static private void checkManager() {
26        Map<Thread, StackTraceElement[]> traces = Thread.getAllStackTraces();
27        boolean found = false;
28
29        for (Map.Entry<Thread, StackTraceElement[]> entry :
30                 traces.entrySet()) {
31            Thread t = entry.getKey();
32            String name = t.getName();
33            if (name.equals("java.lang.ProcessManager")) {
34                System.out.println("process manager: " + t.getState());
35                found = true;
36            }
37        }
38
39        if (! found) {
40            System.out.println("process manager: nonexistent");
41        }
42    }
43}
44