About JDK-8042694

[David Holmes]

On 2/08/2014 11:40 PM, Harshad RJ wrote:
> Hi,
>
> I hit this bug in my own application today:
> https://bugs.openjdk.java.net/browse/JDK-8042694
>
> My app uses the h2 database which installs a shutdown hook. Works fine, but
> while running with JNLP, the shutdown hook thrown an exception, probably
> because the JAR gets closed too early.
>
> I can't find a way to register on the JIRA site, hence posting here.
>
> I would like to know why was the bug closed as "won't fix"?

Not speaking for the webstart folk.

ShutdownHooks are generally very problematic so issues like this are not 
surprising. There's no guarantee that a shutdown hook thread can access 
any "system" services like submitting to the AWT-Event thread, using 
logging, or even (as seems in this case) loading a new class. Trying to 
make system services work better with hooks is sometimes possible but 
also generally very difficult and error-prone. Generally hooks should be 
written to do as little as possible, relying on as few external services 
as possible, and always anticipating failure. It may be that a shutdown 
hook is not the right mechanism for cleaning up the library in this case 
- perhaps it needs to be done explicitly when the app detects that it is 
required to terminate.

Just my 2c.

David

> ​thanks,​
>