[gccsdk] fork/exec problems

John Tytgat John.Tytgat at aaug.net
Wed May 9 10:33:48 PDT 2012

In message <e420538c52.beeb at ron1954.woosh.co.nz>
          Ron <beeb at woosh.co.nz> wrote:

> I dont know if unixlib's version of fork() does this "copy on
> write" or not, or any other details,

As I mentioned in another mail, UnixLib's implementation is rather
simple here.  It just temporary moves parent out of the way (but in
the same application workspace), runs the child and then you have
the return to the parent.

> just that fork()/exec has been
> causing unstability in the past a (few months ago) and now with
> latest svn upgrades stops program completely at the fork()/exec.
> The earlier situation was erratic and I think would be difficult
> to build a small test case to show it happening. It possibly is
> only happening while running a largish program.   
> I am getting a better picture of things now, for example I know
> now that it is fork()/exec causing unstability, and there are 
> obvious advantages to using vfork()/exec in maybe all cases.

IMHO you're drawing the wrong conclusion.  fork+exec on its own is not
causing any unstability by definition.  It is just for your case hitting a
currently unknown problem.  That might be in your program, use, setup
and/or in UnixLib.  As long there isn't attempt made to drill down to the
real issue, we're unable to draw any valid conclusion at all.

John Tytgat, in his comfy chair at home                                 BASS
John.Tytgat at aaug.net                             ARM powered, RISC OS driven

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