[8u60] RFR: 8078470: [Linux] Replace syscall use in os::fork_and_exec with glibc fork() and execve()

[Thomas Stüfe]

Hi David

- would it be possible to use vfork() instead of fork()? Might increase the
chance of fork() succeeding in out-of-memory scenarios. The way fork/execve
is used here is simple enough for vfork().

- would it be possible to print out errno in case fork fails?

Regards, Thomas


On Thu, Apr 23, 2015 at 8:40 AM, David Holmes <david.holmes at oracle.com>
wrote:

> webrev: http://cr.openjdk.java.net/~dholmes/8078470/webrev/
>
> bug: https://bugs.openjdk.java.net/browse/JDK-8078470
>
> For historical reasons, dating back to LinuxThreads, os::fork_and_exec
> uses direct syscalls to perform fork and execve functions. The fork syscall
> has been deprecated on linux for quite some time and some distributions are
> now shipping with deprecated syscalls removed - this results in a ENOSYS
> error and the "OnError" commands that utilize os::fork_and_exec no longer
> work.
>
> The problem was discussed here:
>
> http://mail.openjdk.java.net/pipermail/hotspot-dev/2015-April/017916.html
>
> It seems the concerns surrounding direct use of glibc fork() and exec()
> are no longer legitimate and Martin Buchholz reports that Google replaced
> the syscalls with glibc calls some time ago and have not had any problems.
> So we propose to apply the same change uniformly on Linux.
>
> This is initially going into 8u60 via jdk8u-hs-dev due to time constraints
> on the 8u60 schedule, and an internal limitation preventing me from pushing
> this to 9 right now. But it will be "backported" to 9 ASAP.
>
> Thanks,
> David
>