From: Keith Gaughan <kmgaughan@...>
Date: 2006-09-29T05:49:17+09:00
Subject: Re: continuations across fork?

On Fri, Sep 29, 2006 at 02:10:52AM +0900, Clifford T. Matthews wrote:

> I wrote some code that deliberately uses continuations that cross a
> fork boundary.  When I went to test it, I was surprised by the error:
> "continuation called across trap".  I can think of a few reasons why
> people might not want to use continuations across fork, but not
> knowing Ruby internals particularly well, I couldn't see a reason why
> it should be absolutely prohibited.

Probably because you're attemptin to jumP to part of a completely different
process. Program counters can't jump between processes like that.

You'll have to do what's usually done: set up an IPC channel of some kind
between the parent and child processes (be it a pipe, socket, a mmap'd file
object, SysV shared memory and semaphores, whatever) and get them to talk
to one another.

> I realize there are several other things I could do other than the
> above.  However, I coded up my solution without realizing that you
> can't call a continuation across fork.  Now I'm curious why it's
> disallowed.

K.

-- 
Keith Gaughan -- kmgaughan@eircom.net -- http://talideon.com/
"I told all of my friends how they were losers for running UNIX. They
should switch to NT.... That was more or less my constant refrain until
a single pivotal event changed my life: I actually tried to use NT.
    -- Philip Greenspun