6850720: Allow POSIX_SPAWN to be used for ProcessImpl on Linux

[David Lloyd]

On Sun, Oct 21, 2018 at 7:25 PM Martin Buchholz <martinrb at google.com> wrote:
> As author of the vfork strategy ...  I'm supportive of the directions in this thread.

Great.

> vfork is even (!) less in favor than it used to be, so migrating off of it seems good.  Just make sure we don't bring back the OOM problems or unacceptable overhead from e.g. an second exec.  Create a 100GB heap, then run /bin/true 1000 times.

Tried it and it succeeded without issues.  I didn't use a 100GB heap
though because I don't have that kind of RAM!  But, I created a long
chain of object arrays totalling about 8GB and forced it to stay alive
until after the 1000 execs of /bin/true and it worked fine.

To verify that the program works correctly, I compared the results
with VFORK and FORK.  As expected, VFORK also worked correctly, but
FORK failed with errno=ENOMEM.

-- 
- DML