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From bugzi...@apache.org
Subject DO NOT REPLY [Bug 8510] - shutdown hook does not fire in forked java task under JDK1.4
Date Tue, 15 Jul 2003 07:23:57 GMT
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http://nagoya.apache.org/bugzilla/show_bug.cgi?id=8510

shutdown hook does not fire in forked java task under JDK1.4

conor@cortexebusiness.com.au changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |1.6



------- Additional Comments From conor@cortexebusiness.com.au  2003-07-15 07:23 -------
I have resolved some aspects of this bug, although it mainly applies to Unix
systems (more on that in a minute).

Under Ant 1.5 under Linux, the ProcessDestroyer does not wait for the
terminating processes to complete their shutdowns. If they have anything more
than a trivial shutdown process, it would get truncated as the Ant VM shuts
down. The ProcessDestroyer also blocked Execute.java in the remove() method as
it held the lock on the processes object. So even if the process managed to
generate output, it may not have made it to the Ant output log.

Under Windows and JDK 1.4, the process shutdown hooks are not fired. This is
marked by Sun as "not a bug". See
http://developer.java.sun.com/developer/bugParade/bugs/4485742.html
although http://developer.java.sun.com/developer/bugParade/bugs/4671966.html may
be able to change that.

JDK 1.3 appears to fire the shutdown hook on Windows but it is something of an
illusion as the shutdown is not allowed to complete. If you put this in the
given Demo class' run method

                System.err.println("DEMO shutdown hook fired");
                try {
                    PrintWriter pw
                        = new PrintWriter(new FileOutputStream("test.txt"));
                    Thread.currentThread().sleep(3000);
                    pw.println("Test");
                    pw.close();
                } catch (Exception e) {
                }
                System.err.flush();

you will find that test.txt is created but no content is written. This works
under Linux.

Note that the use of output or error streams to determine if the shutdown hook
has fired or not is suspect. The above file based approach is more conclusive.
This is because the output generated may still be within a couple of Ant stream
processing threads (daemons) which get terminated in the shutdown process.

The Main.java does not really demonstrate a problem. It gives no info about the
firing of the shutdown hook in the subprocess. In fact it has the same behaviour
as Ant - the subprocess shutdown is not fired. It is indeed a JVM bug^H^H^Hfeature.

I'm marking as fixed from Ant's point of view. You need to lobby Sun to address
the shutdown issues under windows.

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