Hi Mandy,
Looks good but I have one query.
At the top-level there are 3 shutdown hooks:
- console hook
- application hooks
- deleteOnExit hook
and they run in this order. The deleteOnExit hook can be added when
shutdown is in progress, so this allows first-use of deleteOnExit during
an application shutdown hook. Okay - that's fine and solves current
problem very neatly.
But the Console hook that restores the echo state runs first, so if the
first use of the console is by an application shutdown hook, or by some
other thread when shutdown has commenced, then we won't restore the
state of the console. I guess that's how it currently works anyway, but
it seems strange. I'm not familiar with the Console but I would have
expected (naively perhaps) the application shutdown hooks to run first
and then any "internal hooks". That way we would always restore the
state (though I guess there is potentially a race with active threads
still using the console).
David
Mandy Chung said the following on 04/18/09 08:05:
6829503: addShutdownHook fails if called after shutdown has commenced.
Webrev at:
http://cr.openjdk.java.net/~mchung/6829503/webrev.00/
I change the Shutdown#add method to take the registerShutdownInProgress
parameter. If set to true, the specified shutdown hook is allowed to be
registered while shutdown is in progress. The method will throw
IllegalStateException if the shutdown process already passes this
slot. DeleteOnExitHook is the last shutdown hook to be invoked and it
will not be invoked until all application shutdown hooks finish (see
ApplicationShutdownHooks.runHooks()). So any file added to the delete
on exit list by the application shutdown hooks will be handled by the
DeleteOnExitHook.
The LoggingDeadlock2.java test passes with this fix. I also add a new
jtreg test to exercise the Console and DeleteOnExitHook being
initialized during application shutdown.
Alan,
I considered your suggestion to make Shutdown#add method to return a
boolean instead of checking the state. I am concerned that if the
caller didn't check the return value and handle properly, it would be
harder to catch the problem. So I keep it to check the state and throw
IllegalStateException.
Thanks
Mandy
