Ok, you're right that it can raise an exception when the calling thread does
not have the security privileges needed. But what if it had them ? Right now
the deadlock comes from the fact is doesn't got back to the caller with an
exception and doesn't end the current thread. My 1st proposal was to have a way
to end the current thread. If you think that is not acceptable and prefer the
exception solution, then something like throw new
IllegalStateException("Shutdown in progress") which is already used when adding
new hooks while shutting down and adjust the System.exit method documentation
accordingly (might be dangerous since it "breaks" actual documented and
implemented contract, might be too heavy for a change).
First things first : do you think this is an issue the JVM has to solve (either
using a destroy-current-thread solution, or a throw-IllegalStateException one),
or do you think this was a hook misuse and maybe would only need maybe a
clearer warning in the hooks's documentation, or do you think we keep
everything as it is because I should have guessed better reading the actual
documentation 😊 ?
My demo code is simple, but the environment in which it happened and being able
to understand the jstack output with lots of frameworks hooking here and there
plus some uncaught exception hanlders kicking in was really really hard. In my
case I ended up having a hook to run a delayed Runtime.halt call, which more
feels like a JVM workaround rather than a framework workaround.
Regards,
Orange Restricted
-----Message d'origine-----
De : David Lloyd <[email protected]>
Envoyé : lundi 25 avril 2022 15:41
À : CATHERINOT Rémi DTSI/PFS <[email protected]>
Cc : [email protected]
Objet : Re: System.exit deadlock if called within a hook
On Mon, Apr 25, 2022 at 8:09 AM <[email protected]> wrote:
> because it would still run finally blocks, which cannot happen for no
> return methods like System.exit and Runtime.halt
FWIW I don't think this is correct. `exit` and `halt` etc. cannot
*return* but they're definitely allowed to throw an exception
(`SecurityException` is presently specified) and thus are allowed to unwind the
stack, even through `finally` blocks.
--
- DML • he/him
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