Request for Review: 5049299: (process) Use posix_spawn, not fork, on S10 to avoid swap exhaustion

[Rob McKenna]

Hi folks,

Looking for a review for the webrev below, which also resolves:

7175692: (process) Process.exec should use posix_spawn [macosx]

For additional context and a brief description it would be well worth 
looking at the following thread started by Michael McMahon, who did the 
brunt of the work for this fix:

http://mail.openjdk.java.net/pipermail/core-libs-dev/2009-May/thread.html#1644

Basically the fix aims to swap fork for posix_spawn as the default 
process launch mechanism on Solaris and Mac OSX in order to avoid swap 
exhaustion issues encountered with fork()/exec(). It also offers a flag 
(java.lang.useFork) to allow a user to revert to the old behaviour.

I'm having trouble seeing the wood for the trees at this point so I'm 
anticipating plenty of feedback. In particular I'd appreciate some 
discussion on:

- The binary launcher name & property name may need some work. A more 
general property ("java.lang.launchMechanism") to allow a user to 
specify a particular call was mooted too. It may be more future proof 
and I'm completely open to that. (e.g. 
launchMechanism=spawn|fork|vfork|clone - we would obviously ignore 
inapplicable values on a per-platform basis)
- I'd like a more robust way of checking that someone isn't trying to 
use jprochelper outside of the context for which it is meant.
- The decision around which call to use getting moved to the java level 
and away from the native preprocessor.

The webrev is at:

http://cr.openjdk.java.net/~robm/5049299/webrev.01/ 
<http://cr.openjdk.java.net/%7Erobm/5049299/webrev.01/>

Thanks a lot,

     -Rob