Re: wip-threads-and-fork

[Nala Ginrut]

On Fri, Feb 24, 2012 at 12:13 AM, Andy Wingo <address@hidden> wrote:

On Thu 23 Feb 2012 16:49, Nala Ginrut <address@hidden> writes:

> I just want to do my negative vote when I saw "choose thead then fork
> die", but I see "open-process" soon. ;-)  So, what's the difference
> between "primitive-fork" and "open-process"? If they're different, I
> think much code to be modified for me...I believe I'm not the only
> layman to use "fork" and "thread" both.  

Open-process is at the guts of the (ice-9 popen) modules.  Open-pipe* is
a thin wrapper around it -- see "Pipes" in the manual.

Basically open-pipe* / open-process does a fork(), and then an exec().
Doing this yourself in Scheme is actually impossible with threads,
because you'll need to take Scheme strings and produce C strings in the
current locale, to pass to the exec call.  That involves malloc, iconv,
and libgc allocation, and none of them are guaranteed to work after a
fork(), in a multithreaded program.

I think I could use pipes to handle some sub-process rather than do it with fork manually. But I must create a daemon, it can't avoid to use fork, will this circumstance cause problems if I use threads after it?

 

Andy
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