RFR: 8288984: Simplification in java.lang.Runtime::exit [v2]

[Ryan Ernst]

On Mon, 4 Jul 2022 12:19:27 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Ryan Ernst has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   better clarify multiple threads behavior
>
>> Let's say we've run shutdown so run all the hooks but not halted. Then someone calls exit(0). That seems to suggest the call will block indefinitely, which is neither desirable nor what was actually implemented.
> 
> If the hook threads do not halt then the exiting thread (which holds the lock) blocks forever in the join(). Any other call to exit blocks trying to acquire the lock. That has always been the way this works - if hook threads don't terminate then the VM doesn't (unless someone calls halt() directly). That is one of the things the window you suggested be closed, allowed - a call to exit(non-zero) could force a call to halt().

I appreciate all the feedback and the many opinions expressed here! This has been a learning exercise for me in finding a balance between implementation and specification. While I still think mentioning the possibility of signals is beneficial to a developer trying to understand that the passed status code could be ignored, the text suggested by @dholmes-ora is better than was previously there, so I have updated this PR with that. See [fccd85b](https://github.com/openjdk/jdk/pull/9351/commits/fccd85ba106ff651c00479446ac3207ed60698e8).

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PR: https://git.openjdk.org/jdk/pull/9351