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Date: Wed, 05 Feb 2014 11:01:50 -0500
From: "Larry Hall (Cygwin)" <reply-to-list-only-lh AT cygwin DOT com>
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To: cygwin AT cygwin DOT com
Subject: Re: using spawn functions to avoid fork() errors
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On 2/5/2014 7:07 AM, Steven Bardwell wrote:
>>From reading the Cygwin FAQ ("In most cases, you are better off using the
> spawn family of calls if possible.") and
> the Cygwin Highlights ("Fortunately, in most circumstances the spawn family
> of calls provided by Cygwin can be substituted for a fork/exec pair with
> only a little effort."), it sounds like there exists a family of API calls
> that may help me avoid the 'Resource temporarily unavailable' errors from calling
> fork().
>
> However, I can't find any documentation on these spawn functions. I recoded
> my application to use
> posix_spawn() but I am getting the same 'Resource temporarily unavailable'
> error so I suspect that it
> is using fork() as well.

posix_spawn() comes from newlib and uses vfork.  You can take a look
at the code on-line for more info:

<http://cygwin.com/cgi-bin/cvsweb.cgi/src/newlib/libc/posix/posix_spawn.c?rev=1.4&content-type=text/x-cvsweb-markup&cvsroot=src>

An alternative that doesn't use fork was discussed here:

<http://cygwin.com/ml/cygwin/2012-01/msg00032.html>

The code referenced isn't part of Cygwin and may or may not work.  I have
no experience with it.  If you choose to use it, forward your comments and
questions directly to the author.

> I did try the 'rebaseall' process to remove the error, but without any
> success. I also checked the BLODA list.
>
> I have no problem doing some recoding of my application to reliably solve my
> issues with fork() -- can you all
> point me in the direction of the 'spawn family of calls'?

See spawn.cc -> 
<http://cygwin.com/cgi-bin/cvsweb.cgi/src/winsup/cygwin/spawn.cc?rev=1.353&content-type=text/x-cvsweb-markup&cvsroot=src>


-- 
Larry

_____________________________________________________________________

A: Yes.
 > Q: Are you sure?
 >> A: Because it reverses the logical flow of conversation.
 >>> Q: Why is top posting annoying in email?

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