An educated guess from me would be that the particular error message you are waiting for
is not actually written to stderror but normal output stream which you never read.
Specifically this part of java.lang.Process documentation "Because some native
platforms only provide limited buffer size for standard input and output streams, failure
to promptly write the input stream or read the output stream of the subprocess may cause
the subprocess to block, or even deadlock. ".
Anton "exuvo" Olsson
[email protected]
On 2022-03-10 15:55, Robert Heller wrote:
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
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Nathan Stratton Treadway - [email protected] - Mid-Atlantic region
Ray Ontko & Co. - Software consulting services - http://www.ontko.com/
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