X-Recipient:	archive-cygwin AT delorie DOT com
DomainKey-Signature:	a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:from:to:subject:date:message-id:references
	:in-reply-to:content-type:content-id:content-transfer-encoding
	:mime-version; q=dns; s=default; b=cg+y8Zc0V/shnV0dhQnZX5r3Zx9l+
	tHCyqUGrIN0GiIzTpqqQndruLDzuuhT3d9WgZ5u1JRrro6xNlIU5QDyQVnodqMti
	MnUtKy60Rc6vsGlqVBBy8iYQjG9j8GH2upxVLB11zp+oc7//gCxnwwNtaKMTJKOt
	gd5L/JNTqof/tw=
DKIM-Signature:	v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:from:to:subject:date:message-id:references
	:in-reply-to:content-type:content-id:content-transfer-encoding
	:mime-version; s=default; bh=hBaCzvJXFdsfx0wwG8R46T05KvU=; b=Aeg
	qFvWuv5L9oQq4Je2nvIcLi+H+4pf2G7MOLqPmUtFjJs8q6g+EC1mDvkiBPGQHdCO
	6q+9peKwt7/U6WdDEW8BsLgc/Xud+2f+cSlvQCM/pTH5b9WVq6fxbXyHwtQCTYLA
	PWt/uBaGnRv2JpcStVxHBbdO7/+OMseZ+qzDw4X8=
Mailing-List:	contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Id:	<cygwin.cygwin.com>
List-Subscribe:	<mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive:	<http://sourceware.org/ml/cygwin/>
List-Post:	<mailto:cygwin AT cygwin DOT com>
List-Help:	<mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender:	cygwin-owner AT cygwin DOT com
Mail-Followup-To:	cygwin AT cygwin DOT com
Delivered-To:	mailing list cygwin AT cygwin DOT com
Authentication-Results:	sourceware.org; auth=none
X-Spam-SWARE-Status:	No, score=-9.3 required=5.0 tests=AWL,BAYES_00,GIT_PATCH_2,NORMAL_HTTP_TO_IP,NUMERIC_HTTP_ADDR,RCVD_IN_DNSWL_NONE,SPF_HELO_PASS,SPF_PASS autolearn=ham version=3.3.1 spammy=
X-HELO:	NAM05-BY2-obe.outbound.protection.outlook.com
ARC-Seal:	i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=HliKE1VMvLruxuUNT/oJE0J3bis9C5BYqDqxpiKNoAHYwRYJSYebwyWqphsqY8zeGXtI2R5QgNhNPD4boC+q0HfHBMR+UrVOk4iAiQP4TD8FDktilXaP7f+U0xR3V9Nezp9MaEzZeiz0LWqnM284WGNlt3NCpaSDNo7fH2GBxfcTtc8yf9Z/+khF2hufvRtn+thx4kuUBTz5OBNDqQseOLel3uVyOXqiEif5xbKQtRr4pyz4Lee8OdB7rbwJVq3JJ0rUIhuwlnaMmxsDploKpLbpdl/A0+KSo1n2ttTsWLIhirq3+skWn70WvFXCqMieeHsImkSDvBbktb/nzp0W3Q==
ARC-Message-Signature:	i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=QX9wKNmLOOyw9qrQYJGN6bPs1sAjyTEsLAYarY5hdds=; b=LyCiEtaU4LYn8Mof2l/ak2s6lJDN2npDpft+79/cQ4hNgdsreWJzSCDLKVGLhNjDnTASggqKsJb+BbU3FOB3ZhjzJcRDyzHMTk7M5W2VTBGa8l03raK7MGrIHSUABv3kdsPUbitBBw9ymvPMuuI8LNg10XSDxaBnVRtFLJqQw8YOvfEfg9tbEZAod4EMUeE8evKdo/avpd7m4SRHFo7rv969h5p4ryKWtnZaxzkW3/29p0RlVhCRLs19kMVIukpzTAXQj7ky4UwBZ6ngCXNApMU/cQcjpQwlxjqWEW3X0akBScmqTqCKfUO4LFYlfXU5zR+C57DO+OPPBpuuWmwK4Q==
ARC-Authentication-Results:	i=1; mx.microsoft.com 1;spf=pass smtp.mailfrom=cornell.edu;dmarc=pass action=none header.from=cornell.edu;dkim=pass header.d=cornell.edu;arc=none
DKIM-Signature:	v=1; a=rsa-sha256; c=relaxed/relaxed; d=cornell.edu; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=QX9wKNmLOOyw9qrQYJGN6bPs1sAjyTEsLAYarY5hdds=; b=N0KwZLq9DJ4gXdABIt130JRz0RzhPEwh3wyDH/hhpmBUCvfn7wgiccz3nsxTY9npOljuNd9nntJS7qNx6t82st42fJHAxlZ1dKFJsPv7MsnknZ2aBKUNqQZSuao+/pv43MfZVbS2VW16QEuEjdRZuhvSlLv8TDKpU8b1/E+UX1c=
From:	Ken Brown <kbrown AT cornell DOT edu>
To:	"cygwin AT cygwin DOT com" <cygwin AT cygwin DOT com>
Subject:	Re: Regression (last snapshot)
Date:	Mon, 29 Jul 2019 13:35:41 +0000
Message-ID:	<0166ad54-5417-054c-b4e3-b2a97cad8ad0@cornell.edu>
References:	<8f6a87faa9c8130241c026889a01d763 AT xs4all DOT nl> <5414d0e1-79d9-cab7-b1bd-4761265bf8bd AT cornell DOT edu> <265a2749-95b6-38aa-a191-7913bfcc98b6 AT cornell DOT edu> <20190722152016 DOT GE21169 AT calimero DOT vinschen DOT de> <20190722155340 DOT GF21169 AT calimero DOT vinschen DOT de> <20190722164509 DOT GG21169 AT calimero DOT vinschen DOT de> <eb8007691b20df0eb8032ca3d2fa445f AT smtp-cloud8 DOT xs4all DOT net> <b3b04db5-7f03-8281-f376-6cd10207ec01 AT cornell DOT edu> <4b59209a91e8384ec000e2724696791c AT smtp-cloud7 DOT xs4all DOT net> <935d8ce5-fd5c-3010-4664-bb2dc9b7ca2f AT cornell DOT edu> <20190729084552 DOT GL11632 AT calimero DOT vinschen DOT de> <eea273ca-f190-c91a-7892-9407bfcf4326 AT cornell DOT edu>
In-Reply-To:	<eea273ca-f190-c91a-7892-9407bfcf4326@cornell.edu>
user-agent:	Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0
authentication-results:	spf=none (sender IP is ) smtp.mailfrom=kbrown AT cornell DOT edu;
x-ms-exchange-purlcount:	1
x-ms-oob-tlc-oobclassifiers:	OLM:9508;
received-spf:	None (protection.outlook.com: cornell.edu does not designate permitted sender hosts)
x-ms-exchange-senderadcheck:	1
MIME-Version:	1.0
X-MS-Exchange-CrossTenant-mailboxtype:	HOSTED
X-MS-Exchange-CrossTenant-userprincipalname:	ksb2 AT cornell DOT edu
X-IsSubscribed:	yes
X-MIME-Autoconverted:	from base64 to 8bit by delorie.com id x6TDaJvp001600

On 7/29/2019 9:18 AM, Ken Brown wrote:
> On 7/29/2019 4:45 AM, Corinna Vinschen wrote:
>> On Jul 27 15:24, Ken Brown wrote:
>>> On 7/27/2019 6:21 AM, Houder wrote:
>>>> On Fri, 26 Jul 2019 22:12:43, Ken Brown  wrote:
>>>>
>>>>> On 7/22/2019 2:47 PM, Houder wrote:
>>>>
>>>>>> The specific regression as reported, has gone.
>>>>>>
>>>>>> 64-@@ uname -a
>>>>>> CYGWIN_NT-6.1 Seven 3.1.0s(0.339/5/3) 2019-07-22 16:43 x86_64 Cygwin
>>>>>> 64-@@ ls -lL <(grep bash .bashrc)
>>>>>> pr-------- 1 Henri None 0 Jul 22 20:36 /dev/fd/63
>>>>>
>>>> Over all the behavior has simularity w/ the error reported by David Karr:
>>>>
>>>>        https://cygwin.com/ml/cygwin/2019-07/msg00150.html
>>>>        ( Piping input from subprocess loses track of temp file )
>>>
>>> Thanks, I hadn't noticed that.
>>>
>>> The situation is more complicated than what I reported.  First, it happens even
>>> in cygwin-3.0.7, as David Karr's report suggests.  Second, it's true that I can
>>> only reproduce it under X11, but the pattern is not as regular as I thought.  I
>>> just ran the ls command 1000 times in an xterm window under cygwin-3.0.7, and I
>>> got the "Broken pipe" error 390 times, with a varying number of consecutive
>>> successful runs between the errors.
>>>
>>> Repeating this under the 20190722 or 20190725 snapshots gave slightly worse
>>> results (close to 500 errors).  Using my own unoptimized build of cygwin1.dll,
>>> the error count went up to about 650.
>>
>> I just tried this myself and I can't reproduce the problem.  1000 runs,
>> no error.
> 
> Interesting.  And you ran this under X11 in an xterm window?
> 
>>> I tried running under gdb, but I couldn't get grep to fail.  More precisely, I
>>> didn't see an error message from grep.  Every run looked like this:
>>>
>>> $ gdb bash
>>> GNU gdb (GDB) (Cygwin 8.2.1-1) 8.2.1
>>> [...]
>>> (gdb) r -c 'ls -lL <(grep bash .bashrc)'
>>> Starting program: /usr/bin/bash -c 'ls -lL <(grep bash .bashrc)'
>>> [...]
>>> pr-------- 1 kbrown None 0 2019-07-27 11:07 /dev/fd/63
>>> [...]
>>> [Inferior 1 (process 21712) exited normally]
>>>
>>> It would be better to be able to debug ls and/or grep, but I don't know how to
>>> get to subprocesses in gdb.  And I think I have to start with 'gdb bash' in
>>> order for the process substitution to happen.
>>
>> Yeah, subprocess debugging is a problem in GDB.  Given how this works,
>> you can at least take grep out of the picture.  Bash is doing all the
>> lifting, so it's just bash and ls.   Did you try to reproduce this under
>> strace?
> 
> Yes, but there I get an error (even under mintty) for a different reason:
> 
> $ strace -o trace.out ls -lL <(grep bash .bashrc)
> ls: cannot access '/dev/fd/63': No such file or directory
> 
> The strace output shows a call to fhandler_process::exists on /proc/45036/fd/63;
> here 45036 is the PID of 'ls'.  And then I see an EBADF error.  But I think
> what's happening here might be that bash is parsing '<(grep bash .bashrc)' too
> soon, so that '/dev/fd/63' isn't related to the 'ls' command.
> 
> By the way, I've just tried a different experiment, in which I simplify the ls
> command to 'ls <(grep bash .bashrc)'.  When I run this under xterm, I get the
> broken pipe error 98% of the time or more.  But it's fine under mintty.

I think I may have more-or-less figured out what's going on.  The "broken pipe" 
error simply means that ls has exited before grep has finished writing.  So grep 
is writing to a pipe that has no readers.  If I replace 'ls' by 'cat', I don't 
get any errors.

It remains a mystery to me why I was seeing the broken pipe only under X11, but 
I don't see any reason to think there's a problem.

Ken

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

- Raw text -