[BUG PROPOSAL]: C++ code that calls JNI_CreateJavaVM can be exited by java

[David Holmes]

On 24/08/2017 4:59 PM, Thomas Stüfe wrote:
> Hi David,
> 
> our mails crossed :)

And unfortunately we each added in a different hotspot mailing list. :)

> <snip>
> 
> 
>         PS3: We should replace these annoying exit(0) calls with code
>         that returns
>         "JNI_SILENT_EXIT", so the C++ code has a chance to finish.
> 
> 
>     We should certainly look at getting rid of the exit() calls.
> 
> 
> Or at least consistently route them through the exit hook if one exists. 
> It would also be nice to indicate to the caller in whether we were able 
> to clean up successfully (or did not do anything important yet) or 
> whether the process is tainted. For example, to allow him to retry 
> CreateJavaVM with different options.

I think these simple cases all occur during argument processing before 
too much of the VM has been initialized. Even so it would probably take 
some effort to try and then allow a second call to JNI_CreateJavaVM to 
proceed due to use of static initializers and onLoad hooks.

Depending on the exact context it may be better if the process loading 
the VM filters out these problematic flags in the first place. They 
really only make sense for CLI invocations.

Cheers,
David
-----

>     Ideally no VM related flag would be of the "report and terminate"
>     type, as the termination aspect really belongs in the launcher. I
>     can imagine a launcher using Dcmds to retrieve "help" strings from
>     subsystems rather than having actual "help" options processed by the
>     VM (somewhat similar t how -version is handled: create VM, extract
>     version info, detach VM. exit launcher). That said it would be
>     somewhat awkward, for example, if the launcher processed -Xlog:help,
>     but the VM processed all other -Xlog arguments.
> 
> 
> This would be a pretty cool feature. It would be nice though if help 
> could be retrieved without creating the VM first.
> 
> ..Thomas
> 
>     Cheers,
>     David
> 
> 
> 
>         Best Regards
> 
>         Adam Farley
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>