Question

I have many istances of a process running

Runtime rt = Runtime.getRuntime();
int i=0;
int arg1;
while(i<10){
    arg1 = i+1;
    Process p = rt.exec("abc.exe "+ arg1);
    i++;
}

Each process is being run with different argument value here arg1 is parameter to that process abc.exe, I want to keep a check on all these processes whether they are running or any of them crashed. In case of crash, I want to restart it. How can I keep track of all these process and periodically check if they are crashing or not?

Can I trace this thing on Linux as well as on windows? Read some articles on it but this one is bit different, since it involves multiple occurrences and have to check on some particular process only…

Answer 1

The Runtime.exec(...) command returns a Process object. You can put your Process objects into a collection and then use the Process.exitValue() method to see if each of the processes has finished. exitValue() throws a IllegalThreadStateException if the process is still running.

So your code could be something like:

List<Process> processes = new ArrayList<Process>();
// noticed I turned your while loop into a for loop
for (i = 0; i < 10 i++) {
    int arg1 = i + 1;
    Process p = rt.exec("abc.exe "+ arg1);
    processes.add(p);
}
...
// watch them to see if any of them has finished
// this can be done periodically in a thread
for (Process process : processes) {
   try {
       if (process.exitValue() != 0) {
           // it did not exit with a 0 so restart it
           ...
       }
   } catch (IllegalThreadStateException e) {
       // still running so we can ignore the exception
   }
}

Can I trace this thing on Linux as well as on windows?

The above code should work on Lunux and Windows if I understand the question.