From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-return-155950-listarch-gcc=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 3379 invoked by alias); 14 Aug 2009 21:17:28 -0000
Received: (qmail 3316 invoked by uid 22791); 14 Aug 2009 21:17:27 -0000
X-SWARE-Spam-Status: No, hits=-2.0 required=5.0 	tests=AWL,BAYES_00,J_CHICKENPOX_83
X-Spam-Check-By: sourceware.org
Received: from smtp23.services.sfr.fr (HELO smtp23.services.sfr.fr) (93.17.128.20)     by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Fri, 14 Aug 2009 21:17:20 +0000
Received: from filter.sfr.fr (localhost [127.0.0.1]) 	by msfrf2324.sfr.fr (SMTP Server) with ESMTP id 0056D7000090; 	Fri, 14 Aug 2009 23:17:18 +0200 (CEST)
Received: from [192.168.1.101] (197.156.90-79.rev.gaoland.net [79.90.156.197]) 	by msfrf2324.sfr.fr (SMTP Server) with ESMTP id 7DF107000087; 	Fri, 14 Aug 2009 23:17:17 +0200 (CEST)
X-SFR-UUID: 20090814211717515.7DF107000087@msfrf2324.sfr.fr
Subject: Re: Need some Unix and /bin/sh expertise for GCC testsuite
From: Laurent GUERBY <laurent@guerby.net>
Reply-To: laurent@guerby.net
To: Dave Korn <dave.korn.cygwin@googlemail.com>
Cc: gcc <gcc@gcc.gnu.org>, Paolo Bonzini <bonzini@gnu.org>, Arnaud Charlet <charlet@adacore.com>, Eric Botcazou <ebotcazou@adacore.com>
In-Reply-To: <4A85D4EE.7040503@gmail.com>
References: <1250283155.20287.116.camel@localhost> 	 <4A85D4EE.7040503@gmail.com>
Content-Type: text/plain
Date: Fri, 14 Aug 2009 21:37:00 -0000
Message-Id: <1250284636.20287.123.camel@localhost>
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
X-IsSubscribed: yes
Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc/>
List-Post: <mailto:gcc@gcc.gnu.org>
List-Help: <http://gcc.gnu.org/ml/>
Sender: gcc-owner@gcc.gnu.org
X-SW-Source: 2009-08/txt/msg00248.txt.bz2

On Fri, 2009-08-14 at 22:19 +0100, Dave Korn wrote:
> Laurent GUERBY wrote:
> 
> > 3/ Here is the point I find surprising: the "ps fauxww" run in the
> > second "if" show that even if the script is fully sequential
> > at least one gnatmake subprocess (collect-ld) is still marked as running 
> > *in parallel* with the ps command in the subsequent "if" of the script!
> 
> > Any idea of why /bin/sh is running stuff in parallel instead
> > of sequential? 
> > 
> > Could some code in 
> > gnatmake/gnatlink/xgcc/collect2/collect-ld cause it?
> 
>   I notice gnatmake.adb has a reference to GNAT.OS_Lib.Non_Blocking_Spawn in
> it.... coincidence?

gnatmake uses Non_Blocking_Spawn to call the compiler (gnatmake supports
"-j N" like make), but for the gnatlink call (we see in the "ps fauxww")
it uses in gcc/ada/make.adb:

   procedure Link
...
      GNAT.OS_Lib.Spawn (Gnatlink_Path.all, Link_Args, Success);
   end Link;

which ends up calling gcc/ada/s-os_lib.adb

      Spawn_Internal (Program_Name, Args, Result, Junk, Blocking =>
True);
...
         function Portable_Spawn (Args : Address) return Integer;
         pragma Import (C, Portable_Spawn, "__gnat_portable_spawn");

which ends up calling in gcc/ada/adaint.c:

int
__gnat_portable_spawn (char *args[])
...
  pid = fork ();
  if (pid < 0)
    return -1;

  if (pid == 0)
    {
      /* The child. */
      if (execv (args[0], MAYBE_TO_PTR32 (args)) != 0)
	_exit (1);
    }

  /* The parent.  */
  finished = waitpid (pid, &status, 0);

  if (finished != pid || WIFEXITED (status) == 0)
    return -1;

  return WEXITSTATUS (status);
}

Thanks for your help :).

Laurent