DMARC-Filter: OpenDMARC Filter v1.4.2 delorie.com 56I8jv1v2437578
Authentication-Results: delorie.com; dmarc=pass (p=none dis=none) header.from=cygwin.com
Authentication-Results: delorie.com; spf=pass smtp.mailfrom=cygwin.com
DKIM-Filter: OpenDKIM Filter v2.11.0 delorie.com 56I8jv1v2437578
Authentication-Results: delorie.com;
	dkim=pass (1024-bit key, unprotected) header.d=cygwin.com header.i=@cygwin.com header.a=rsa-sha256 header.s=default header.b=sNiV3zbY
X-Recipient: archive-cygwin AT delorie DOT com
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org CEA89385F00F
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cygwin.com;
	s=default; t=1752828356;
	bh=PYdFx97YkYL3fVRCh4gzwBGLzZWABD+W1LMtaWfwyso=;
	h=Date:To:Subject:In-Reply-To:References:List-Id:List-Unsubscribe:
	 List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:
	 From;
	b=sNiV3zbYEVvqTzY0Z4BEoaUGHlcPa5Qz+uuLlPRhRCM30IhW1DeujXA2/2L4GzCA1
	 Am6+dpJE9h4W7o2UpjW2wDTDerUMg4lxpYcgnabCpFzH6kQzi8XkFaUCAGKpeN2uQL
	 BMIzUp5KdX7//ElMnnwG8p9GEVkrLSNt/L01SyVk=
X-Original-To: cygwin AT cygwin DOT com
Delivered-To: cygwin AT cygwin DOT com
DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 079D0385F027
ARC-Filter: OpenARC Filter v1.0.0 sourceware.org 079D0385F027
ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1752828071; cv=none;
 b=YFQzAs+fce0hbkGk3j5Jq/Thz6TKDP119UIdA3BAf0xVLEh7ZCbnBKVJQMi7iIXsQ+4XGT3eGJT5YONidFJ2JRM0VTyjNNMitqKImQNkVTBuAnXBvF8QxpbbqWcoUNor8o8mPwWu/qEoZGcR08b9WrwNGjgWa5aRnYV4m+4moCU=
ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key;
 t=1752828071; c=relaxed/simple;
 bh=U8FfF0WUNHiiladOVhvzzSBxR+7WoE1L3g0uzXhZAgA=;
 h=Date:From:To:Subject:Message-Id:Mime-Version:DKIM-Signature;
 b=g6ksxEmy+auvvBLVLQ+trJ1LpwUQE8D964+xDFOY795AbGmJVtef5edx2UWcPLBzSpo284vwnCp9uLiwk50dwNR/6YN/KgdAJPWLfVyZdrV9lZtUbELF4KMgPct8F/hYZlaDu/bECjeJk0IccANYBnHVdkvpuQ0xUIIuIEk2N8s=
ARC-Authentication-Results: i=1; server2.sourceware.org
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 079D0385F027
Date: Fri, 18 Jul 2025 17:41:08 +0900
To: cygwin AT cygwin DOT com
Subject: Re: Calling system() in multi-threads.
Message-Id: <20250718174108.9044c793dc3363562a80833b@nifty.ne.jp>
In-Reply-To: <aHn871v7YwBUOQfs@calimero.vinschen.de>
References: <20250617215411 DOT ebf69d1c18b55191a1b76c01 AT nifty DOT ne DOT jp>
 <eb7786ee-dc7a-4689-9d17-b842e581d7c7 AT maxrnd DOT com>
 <20250618203127 DOT 71ac180de11230a9a6055185 AT nifty DOT ne DOT jp>
 <20250716235236 DOT 96055ec145d9a0528b50c357 AT nifty DOT ne DOT jp>
 <aHfHCqD2xZcdyu7u AT calimero DOT vinschen DOT de>
 <20250717231421 DOT 56b54f7e96266311101d4c08 AT nifty DOT ne DOT jp>
 <aHkUldQHKjA-lZrw AT calimero DOT vinschen DOT de>
 <20250718004446 DOT 9ce9f7f208566ded1a676fd5 AT nifty DOT ne DOT jp>
 <aHn871v7YwBUOQfs AT calimero DOT vinschen DOT de>
X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.30; i686-pc-mingw32)
Mime-Version: 1.0
X-BeenThere: cygwin AT cygwin DOT com
X-Mailman-Version: 2.1.30
Precedence: list
List-Id: General Cygwin discussions and problem reports <cygwin.cygwin.com>
List-Unsubscribe: <https://cygwin.com/mailman/options/cygwin>,
 <mailto:cygwin-request AT cygwin DOT com?subject=unsubscribe>
List-Archive: <https://cygwin.com/pipermail/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-request AT cygwin DOT com?subject=help>
List-Subscribe: <https://cygwin.com/mailman/listinfo/cygwin>,
 <mailto:cygwin-request AT cygwin DOT com?subject=subscribe>
From: Takashi Yano via Cygwin <cygwin AT cygwin DOT com>
Reply-To: Takashi Yano <takashi DOT yano AT nifty DOT ne DOT jp>
Content-Type: text/plain; charset="utf-8"
Errors-To: cygwin-bounces~archive-cygwin=delorie DOT com AT cygwin DOT com
Sender: "Cygwin" <cygwin-bounces~archive-cygwin=delorie DOT com AT cygwin DOT com>
Content-Transfer-Encoding: 8bit
X-MIME-Autoconverted: from base64 to 8bit by delorie.com id 56I8jv1v2437578

On Fri, 18 Jul 2025 09:51:11 +0200
Corinna Vinschen via Cygwin <cygwin AT cygwin DOT com> wrote:

> On Jul 18 00:44, Takashi Yano via Cygwin wrote:
> > On Thu, 17 Jul 2025 17:19:49 +0200
> > Corinna Vinschen wrote:
> > > On Jul 17 23:14, Takashi Yano via Cygwin wrote:
> > > > Hi Corinna,
> > > > 
> > > > On Wed, 16 Jul 2025 17:36:42 +0200
> > > > Corinna Vinschen wrote:
> > > > > On Jul 16 23:52, Takashi Yano via Cygwin wrote:
> > > > > > Do you have any idea?
> > > > > 
> > > > > Locking would be super-simple.
> > > > > 
> > > > > But theoretically it should be possible to use a local child_info_spawn
> > > > > variable at this point.  The ch_spawn child_info_spawn instance is not
> > > > > copied to the child anyway, so that should be safe.  The same goes for
> > > > > posix_spawn() then, btw.
> > > > > 
> > > > > I checked the sources and I don't see any dependency to ch_spawn
> > > > > from a spawning process, in contrast to an exec'ing process.  That
> > > > > doesn't mean there is none, just that I didn't find any.
> > > > 
> > > > Thanks!
> > > > As a starting point, I tried tntroducing locking. It almost works
> > > > as expected, however, sometimes my STC in my first report is hangs
> > > > if N is large e.g. 100. The patch is as attached.
> > > > 
> > > > What am I missing?
> > > 
> > > I don't know.  You're perhaps not releasing the lock in all cases.
> > > But I would have to debug this just like you ¯\_(ツ)_/¯
> > > 
> > > Out of curiosity, did you try using a locale child_info_spawn instance
> > > instead?  That would be a rather nice solution, but I'm pretty sure
> > > there's some other problem lurking in the dark...
> > 
> > I'm not sure what to do with local child_info_spawn.
> > Some of other modules refer to ch_spawn, such as exception.cc and
> > pinfo.cc. Also, has_execed* uses ch_spawn. What should we do for that?
> 
> Yes, that's what I meant with my above paragraph, i.e.
> 
> > > > > I checked the sources and I don't see any dependency to ch_spawn
> > > > > from a spawning process, in contrast to an exec'ing process.  That
> > > > > doesn't mean there is none, just that I didn't find any.
> 
> These external dependencies *should* only be of interest when performing
> an execve, but not when performing a spawnve.

So, the previous patch might not correct.
The following makes more sense, I suppose.

diff --git a/winsup/cygwin/spawn.cc b/winsup/cygwin/spawn.cc
index cb58b6eed..56fca6e45 100644
--- a/winsup/cygwin/spawn.cc
+++ b/winsup/cygwin/spawn.cc
@@ -944,6 +944,7 @@ spawnve (int mode, const char *path, const char *const *argv,
   int ret;
 
   syscall_printf ("spawnve (%s, %s, %p)", path, argv[0], envp);
+  child_info_spawn ch_spawn_local;
 
   if (!envp)
     envp = empty_env;
@@ -961,7 +962,7 @@ spawnve (int mode, const char *path, const char *const *argv,
     case _P_WAIT:
     case _P_DETACH:
     case _P_SYSTEM:
-      ret = ch_spawn.worker (path, argv, envp, mode);
+      ret = ch_spawn_local.worker (path, argv, envp, mode);
       break;
     default:
       set_errno (EINVAL);

-- 
Takashi Yano <takashi DOT yano AT nifty DOT ne DOT jp>

-- 
Problem reports:      https://cygwin.com/problems.html
FAQ:                  https://cygwin.com/faq/
Documentation:        https://cygwin.com/docs.html
Unsubscribe info:     https://cygwin.com/ml/#unsubscribe-simple