RFR: JDK-8262955: Unify os::fork_and_exec() across Posix platforms [v3]

[David Holmes]

On 8/03/2021 4:12 pm, Thomas Stuefe wrote:
> On Mon, 8 Mar 2021 05:37:37 GMT, David Holmes <dholmes at openjdk.org> wrote:
> 
>>> Thomas Stuefe has updated the pull request incrementally with one additional commit since the last revision:
>>>
>>>    tidy up
>>
>> src/hotspot/share/runtime/thread.hpp line 826:
>>
>>> 824:   static void SpinRelease(volatile int * Lock);
>>> 825:
>>> 826: #ifdef POSIX
>>
>> I hate seeing this in shared code. It really belongs in platform-dependent thread code - but osThread_posix doesn't exist. :(
>>
>> But do we need this - can't the existing use_vfork_if_available parameter instead be renamed and interpreted as not_in_a_signal_handler?
> 
> But would having this functionality not make sense? We always argue about what is and is not allowed during signal handling; here, we may get a mechanism to actually assert it and e.g. prevent using malloc() or logging or whatever VM functionality may creep in.

I agree having IsInSignalHandler may be generally useful, my issue was 
with how you actually did it - in the shared code - and so simpler 
solution for the currnet case would just be to reuse the existing para,eter.
> 
> But I will revert my last commit completely and re-add the needs-vfork parameter. This was supposed to be mainly a cleanup; maybe it was wrong to mix in behavioral changes.

True. Do the refactoring then look at enhancements later. Sorry for 
making this harder.

Cheers,
David

> -------------
> 
> PR: https://git.openjdk.java.net/jdk/pull/2810
>