Re: Problem with amtape "hanging" when forked from Java

At Wed,  9 Mar 2022 22:50:29 -0500 (EST) Robert Heller <[email protected]> wrote:

> 
> At Wed, 9 Mar 2022 19:11:40 -0500 Nathan Stratton Treadway <[email protected]> wrote:
> 
> > 
> > On Tue, Mar 08, 2022 at 18:27:47 -0500, Robert Heller wrote:
> > > 
> > > I've written a Java program that goes through vaulted tapes and forks amtape 
> > > (using Runtime.getRuntime().exec(()), and when a non-existant tape label is 
> > > asked for, amtape "hangs".  I cannot figure out why or how to get amtape to 
> > > just exit with an error (which I can then handle).
> > 
> > Does it still hang if you pass an argument "-ointeractivity=''" when you
> > exec amtape?
> 
> Did not try that.

OK, it still hangs.

Here is the Java fragment:

public class FlushOldVaults extends BackupVault {
    private static final String AMTAPE = "/usr/sbin/amtape";
    private static final String AMTAPEOPT1 = "-otpchanger=vault_changer";
    private static final String AMTAPEOPT2 = "-ointeractivity=";
    private String amtape(String tape) throws Exception {
        String cmd[] = new String[6];
        cmd[0] = AMTAPE;
        cmd[1] = AMTAPEOPT1;
        cmd[2] = AMTAPEOPT2;
        cmd[3] = configuration.AMCONFIG();
        cmd[4] = "label";
        cmd[5] = tape;
        System.err.printf("*** FlushOldVaults.amtape(): tape is '%s'\n",tape);
        Process p = Runtime.getRuntime().exec(cmd);
        InputStream err = p.getErrorStream();
        if (err != null) err.readAllBytes();
        if (!p.waitFor(60L, java.util.concurrent.TimeUnit.SECONDS)) {
            System.err.printf("*** FlushOldVaults.amtape(): process timeout\n");
            String kill[] = new String[2];
            kill[0] = "/bin/kill";
            Long j = new Long(p.pid());
            kill[1] = j.toString();
            Process killproc = Runtime.getRuntime().exec(kill);
            killproc.waitFor();
        }
        int status = p.waitFor();
        System.err.printf("*** FlushOldVaults.amtape(): status = %d\n",status);
        if (status != 0) throw new Exception(AMTAPE+" "+AMTAPEOPT1+" "+AMTAPEOPT2+" "+configuration.AMCONFIG()+" label "+tape+": failed");
        String tpchanger = amgetconf("CHANGER:vault_changer:tpchanger");
        int colon = tpchanger.indexOf(':');
        if (colon < 0) {
            return tpchanger+"/data/";
        } else {
            return tpchanger.substring(colon+1)+"/data/";
        }
    }
}


> 
> > 
> > If it does still hang, what do "lsof -p" and "strace -p" show on the
> > amtape process while it's stuck?
> > 
> > 							Nathan
> > 
> > ----------------------------------------------------------------------------
> > Nathan Stratton Treadway  -  [email protected]  -  Mid-Atlantic region
> > Ray Ontko & Co.  -  Software consulting services  -   http://www.ontko.com/
> >  GPG Key: http://www.ontko.com/~nathanst/gpg_key.txt   ID: 1023D/ECFB6239
> >  Key fingerprint = 6AD8 485E 20B9 5C71 231C  0C32 15F3 ADCD ECFB 6239
> > 
> >                   
> > 
> 

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