DMARC-Filter:	OpenDMARC Filter v1.4.2 delorie.com 56I8jgdL2437269
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 56I8jgdL2437269
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=KNCPbvIM
X-Recipient:	archive-cygwin AT delorie DOT com
DKIM-Filter:	OpenDKIM Filter v2.11.0 sourceware.org 11F37385EC3B
DKIM-Signature:	v=1; a=rsa-sha256; c=relaxed/relaxed; d=cygwin.com;
	s=default; t=1752828342;
	bh=PvKB5A100jdFTtEXH4I2Fa2DiPukKFnrCiB/Yyvu+rM=;
	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=KNCPbvIMY0PNyV6xEpw2sRiHsx591PSFopa6jBihv/OH/C7dxXGnDMHiI0m/giR4c
	C8ydF0GiY0v/4C+SH5XBgopfCrGBXaaGxyeNckGvoje6JAjThYBksucqcFlIqbuKSb
	zTlSrx/o8wXmKOf+OwtPsKfr40UPPUlKERWOTvbA=
X-Original-To:	cygwin AT cygwin DOT com
Delivered-To:	cygwin AT cygwin DOT com
DMARC-Filter:	OpenDMARC Filter v1.4.2 sourceware.org 2001D385F032
ARC-Filter:	OpenARC Filter v1.0.0 sourceware.org 2001D385F032
ARC-Seal:	i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1752828171; cv=none;
	b=pLK3U8roNCReVdLppBTWm12u/KD8oEGM4L/W54xx04u32KAzna7T9+S5r2keZs3JGGn06Mw4GZj9KsKz7p6u63+JFaYCS668s/rAqf69K7ja6Fkxqa8Qi6/PMtSVaRdTbC5Nvh7aH2eSMBLgGHNJ7Ct75Ah+Doq8sW4xBlfr+q0=
ARC-Message-Signature:	i=1; a=rsa-sha256; d=sourceware.org; s=key;
	t=1752828171; c=relaxed/simple;
	bh=3Ha3S7pNwOxVUsf6/yaiAR0Z/CR1aZHDIHymwnoW1F8=;
	h=Date:From:To:Subject:Message-Id:Mime-Version:DKIM-Signature;
	b=ZDnIWqubHApsS4fCnh2lh0kKSuwMFm/67ZjmPIA+44njP/1eJ/BNUNxxQf3NUBv3tDtD9Ze/ss+R7R6iT3moMu3CV/FeNTFzvV8dE1vTBruSeCU2sPDC7Rs2J1wUSulnCkgBFgta0Px5Xd83hcFeTjcjIg9ml2h0nBd1ltyTyrQ=
ARC-Authentication-Results:	i=1; server2.sourceware.org
DKIM-Filter:	OpenDKIM Filter v2.11.0 sourceware.org 2001D385F032
Date:	Fri, 18 Jul 2025 17:42:47 +0900
To:	cygwin AT cygwin DOT com
Subject:	Re: Calling system() in multi-threads.
Message-Id:	<20250718174247.5e3328ab5a9e25e42d3e4fcb@nifty.ne.jp>
In-Reply-To:	<aHn9rNKV85wagDCC@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>
	<20250718012800 DOT 45ae0a80ff8bcd286c176baa AT nifty DOT ne DOT jp>
	<aHn9rNKV85wagDCC 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
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>
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>
X-MIME-Autoconverted:	from base64 to 8bit by delorie.com id 56I8jgdL2437269

On Fri, 18 Jul 2025 09:54:20 +0200
Corinna Vinschen wrote:
> On Jul 18 01:28, Takashi Yano via Cygwin wrote:
> > On Fri, 18 Jul 2025 00:44:46 +0900
> > Takashi Yano 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?
> > > 
> > > I've just tried simply the following patch, however, this also hangs
> > > with my STC.
> > > 
> > > 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;
> > > @@ -951,7 +952,7 @@ spawnve (int mode, const char *path, const char *const *argv,
> > >    switch (_P_MODE (mode))
> > >      {
> > >      case _P_OVERLAY:
> > > -      ch_spawn.worker (path, argv, envp, mode);
> > > +      ch_spawn_local.worker (path, argv, envp, mode);
> > >        /* Errno should be set by worker.  */
> > >        ret = -1;
> > >        break;
> > > @@ -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);
> > 
> > The hang seems to be at acquiring the cygheap_protect lock in child sh.exe.
> > This lock is aquired only in _cfree() and _cmalloc(), so I am not sure why
> > cygheap_protect cannot be acquired at this point at all...
> 
> How do the affected backtraces look like?
> 
> Also, one reason could be that cygheap_protect is a SRWLOCK  since
> 5d3e79ec6bb73 ("Cygwin: cygheap: use SRWLOCK for cygheap locking")
> 
> SRWLOCK is not recursive.  What if you revert this lock to a muto as
> before 5d3e79ec6bb73?

Thanks! I'll try muto.

-- 
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

- Raw text -