RFR: JDK-8274320: os::fork_and_exec() should be using posix_spawn

[Thomas Stuefe]

On Sun, 31 Oct 2021 22:06:31 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Hi, may I have reviews for this small patch please?
>> 
>> `os::fork_and_exec()`, used in the hotspot to spawn child programs (scripts etc) in error situations, should be using `posix_spawn()`. 
>> 
>> ATM it uses either `fork()` or `vfork()`. `vfork()` got deprecated on MacOS and we get build errors (JDK-8274293) - even though in this case it would be completely fine to use. This leaves us with `fork()` for MacOS, which has the known problems with large-footprint-parents. This matters here especially since we also use os::fork_and_exec to implement `-XX:OnError` for OOM situations.
>> 
>> We already use posix_spawn() as default for Runtime.exec() since JDK 15, and it is available on all our Unices. We also should use it here.
>> 
>> I kept the name of the function (fork_and_exec) since people know it, even though it's more incorrect now than before.
>> 
>> Tests:
>> - manual tests using -XX:OnError with various scripts, including checking that env variables are passed correctly
>> - manually ran runtime/ErrorHandling tests
>> - GHAs
>
> Hi Thomas,
> 
> I've approved it so we can start baking it. I hope it will get sufficient test coverage.
> 
> Thanks,
> David

Thanks @dholmes-ora. We should extend the OnError tests somewhat.

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PR: https://git.openjdk.java.net/jdk/pull/5698