Re: ProcessBuilder.start() without waiting?

From:

Andrea Francia <andrea.francia@gmx.REMOVE_FROM_HERE_ohohohioquesto?datogliereohohoho_TO_HERE.it>

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 14 Aug 2008 19:20:52 +0200

Message-ID:

<48a46974$0$18150$4fafbaef@reader3.news.tin.it>

Steve Sobol wrote:

On 2008-08-14, Andrea Francia <andrea.francia@gmx.REMOVE_FROM_HERE_ohohohioquesto?datogliereohohoho_TO_HERE.it> wrote:

Steve Sobol wrote:

I'd like to execute an external program using start() but the JVM waits until
the executed program exits before continuing execution.

This is strange. Post the code so someone could review it.

String path = dt.getUpdateFile().getAbsolutePath();
    System.out.println("Path: " + path + "/" +
        dt.getUpdateFile().getParent());
    ProcessBuilder pb = new ProcessBuilder("start",path);
    pb.start();

I think you should read (and maybe discard) the standard output and
error of the child process otherwise it may hang waiting when the buffer
became empty.

You can use something like that to discard the standard output:

03 (new Thread() {
04 public void run() {
05 try {
06 while(process.getInputStream().read()!=-1);
07 } catch (IOException ex) {
08 }
09 }}).start();

The same thing is true for the standard error. But in this case you can
use the ProcessBuilder#redirectErrorStream(true)

System.exit(0); // Does not get executed until the called prog ends

To avoid this:

Under linux use the "nohup" utility that detaches the subprocess from
its parent and attach under the init process (PID=1).

Under Windows, I don't know, I thought that using the 'start' command
will suffice.

--
Andrea Francia
http://www.andreafrancia.it/