We've had that problem here as well with amtape. It is hard to reproduce.
If it helps... I've recreated only once *and* .... it was in perl's DESTRUCTORs
that it ran.
At least that's what I thought I could see via gdb. If someone can recreate
this consistently I'd really be glad to try and fix it.
As it is ... we will work soon on a solution to the tape locks such that a new
lock can detect that all old ones are stale or useless and remove them. That
is our current planned workaround for amtape.
-- CH
> -----Original Message-----
> From: [email protected] <owner-amanda-
> [email protected]> On Behalf Of Exuvo
> Sent: Thursday, March 10, 2022 8:22 PM
> To: Robert Heller <[email protected]>
> Cc: Nathan Stratton Treadway <[email protected]>; ? amanda users
> <[email protected]>
> Subject: Re: Problem with amtape "hanging" when forked from Java
>
> Also don't use stream.readAllBytes, it will block until the stream end is
> reached
> ie the process exits and closes the stream. Which completely defeats the
> purpose of the waitFor.
>
> I suggest using something like:
>
> Process p = Runtime.getRuntime().exec(cmd); long start =
> System.currentTimeMillis(); InputStream out = p.getInputStream(); InputStream
> err = p.getErrorStream();
>
> while (p.isAlive() && System.currentTimeMillis() - start < 60 * 1000) {
> if(out != null) {
> int avail = out.available();
> out.skip(avail); // or a read if you want the data
> }
> if(err != null) {
> int avail = err.available();
> err.skip(avail); // or a read if you want the data
> }
> Thread.sleep(1);
> }
>
> Anton "exuvo" Olsson
> [email protected]
>
> On 2022-03-11 04:05, Exuvo wrote:
> > 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
> >>>>
> >>>> -------------------------------------------------------------------
> >>>> --------- Nathan Stratton Treadway - [email protected] -
> >>>> Mid-Atlantic region Ray Ontko & Co. - Software consulting
> >>>> services -
> https://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.on
> tko.com%2F&data=04%7C01%7Cchris.hassell%40betsol.com%7C4ecf8c0cf
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> 0%7C637825657540576785%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjA
> wMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sda
> ta=bNjOVKKGYm3iBIIV1BQk7qBo9Pr6yHUI%2BEPh4gjdDRc%3D&reserved=
> 0
> >>>> GPG Key:
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> 2uro%3D&reserved=0 ID: 1023D/ECFB6239
> >>>> Key fingerprint = 6AD8 485E 20B9 5C71 231C 0C32 15F3 ADCD ECFB
> >>>> 6239
> >>>>
> >>>>
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