X-Recipient:	archive-cygwin AT delorie DOT com
DKIM-Filter:	OpenDKIM Filter v2.11.0 sourceware.org 6C7F43857832
DKIM-Signature:	v=1; a=rsa-sha256; c=relaxed/relaxed; d=cygwin.com;
	s=default; t=1636567494;
	bh=vkpCvJBUke6K/sLqfqlbYwOJxXRB9j5pLJWA0gfWy9c=;
	h=Date:Subject:To:References:In-Reply-To:List-Id:List-Unsubscribe:
	List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc:
	From;
	b=yE8rcgtpkLAxirdUkbzSvrsaHHjEnEG57UI4OL1x3u10aPnsrmfs31N782EvuQU5c
	owRVyxnOCYy0lbD+An4U06ojXWfosVhEwHjZz5dufCv44rCjylxVJDKPefLlNDauw4
	BANuw25JQclTLVeaovSu8+et/eF9Rqqwm73KDpkY=
X-Original-To:	cygwin AT cygwin DOT com
Delivered-To:	cygwin AT cygwin DOT com
DMARC-Filter:	OpenDMARC Filter v1.4.1 sourceware.org 338CE385803F
ARC-Seal:	i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none;
	b=TWqXuqbSAoG1sNr4XegLx5qdfkS4PWhfo5GowUlLKZ/j+u7kBGpHTBtT6RkOJmbzE0ALm4o+QjatczmWNF8WWRgDLGWZ1kIbSFeV5pVn1ty0mS4K03tbPvUrv4tRkH4Mirt+Ccy0Q+s6Zl/607su6+Cyh5XCBmCZg20OKaqnAbiGJmq8L3lOoS3TSdhfUlJxDEPyxRr3P+FpEwi7JiNwNnJciLOZY5HujKor2E90dWwncu8pwRsqeq2uI4gYT6r6e255F2JLsdTqYbjazsoWRoMNDPHgCr/0v0raYlnWWgbmC1JLvkD8ebYRb2znTsneFwEvnF2OUInahGU8Zkq9vw==
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-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1;
	bh=oZBqpi/SNv/BK/xXYU9AZz4bfwpbmxwBSL9cBW2euds=;
	b=ntwmYLCCmidO4QebIEMzZ4bHzqBms/MdsNgvg9jWm9YUSqhH0yjZtC4F/rZZUsmtD6LV7FD0DE0EToNrH8vZXElFQ1IyxChowbdRezR1SVTJUk90amdBRZMoGm90XNhYuyrNmLfcXGo4cH+e2bf1rVJ2X63sXP3obzJlW7X9jKbKxMtzZzDRNgpk2Nz3Q91IupNRa+1ExlvvH5p8ngXcdloHRlvbgp8TbTpmw+CLNGuWuMfJqrchQER5JyLs+m1EtUs2Q2EKOo6vR1VRWQLI3xjDpl/1AhHPBj0OFnskKanUHACK8FnH4+irnG9L4xpea0UuTiA/Ong131k5VdJrKw==
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
Message-ID:	<83df50b8-5c0c-41b9-1e9e-4ea6bfa3d69f@cornell.edu>
Date:	Wed, 10 Nov 2021 13:03:09 -0500
User-Agent:	Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101
	Thunderbird/91.3.0
Subject:	Re: Another pipe-related problem?
To:	"Henry S. Thompson" <ht AT inf DOT ed DOT ac DOT uk>
References:	<f5br1bqaj11 DOT fsf AT ecclerig DOT inf DOT ed DOT ac DOT uk>
	<05c4180e-396b-4af3-ac0c-2ab8125df17e AT cornell DOT edu>
	<f5bk0hh8uox DOT fsf AT ecclerig DOT inf DOT ed DOT ac DOT uk>
	<eb8d7d4f-d1ed-6f30-2ac3-1b24166243d9 AT cornell DOT edu>
	<0971ace1-5ee8-bdcc-5fd9-4551b294ebf8 AT cornell DOT edu>
	<75197fd0-d5da-3236-a7df-b8ffc3f67da7 AT cornell DOT edu>
	<bb6c5229-ce46-5fb3-c8c3-a19c0826d8d5 AT cornell DOT edu>
	<4b937b32-e348-19d2-2406-c55fa12e20a3 AT cornell DOT edu>
	<f5bfss33oxi DOT fsf AT ecclerig DOT inf DOT ed DOT ac DOT uk>
In-Reply-To:	<f5bfss33oxi.fsf@ecclerig.inf.ed.ac.uk>
X-ClientProxiedBy:	BL1PR13CA0426.namprd13.prod.outlook.com
	(2603:10b6:208:2c3::11) To BN7PR04MB4388.namprd04.prod.outlook.com
	(2603:10b6:406:f8::19)
MIME-Version:	1.0
X-MS-PublicTrafficType:	Email
X-MS-Office365-Filtering-Correlation-Id:	b76e0ed2-7ddb-47de-4089-08d9a4745b87
X-MS-TrafficTypeDiagnostic:	BN8PR04MB5617:
X-Microsoft-Antispam-PRVS:	<BN8PR04MB56171841A93EDE09E93D3A23D8939 AT BN8PR04MB5617 DOT namprd04 DOT prod DOT outlook DOT com>
X-MS-Oob-TLC-OOBClassifiers:	OLM:10000;
X-MS-Exchange-SenderADCheck:	1
X-MS-Exchange-AntiSpam-Relay:	0
X-Microsoft-Antispam:	BCL:0;
X-Microsoft-Antispam-Message-Info:	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
X-Forefront-Antispam-Report:	CIP:255.255.255.255; CTRY:; LANG:en; SCL:1; SRV:;
	IPV:NLI; SFV:NSPM; H:BN7PR04MB4388.namprd04.prod.outlook.com; PTR:; CAT:NONE;
	SFS:(4636009)(366004)(31686004)(508600001)(316002)(296002)(3480700007)(66556008)(75432002)(6916009)(2906002)(5660300002)(38100700002)(36756003)(186003)(31696002)(2616005)(6486002)(66476007)(86362001)(8676002)(8936002)(53546011)(66946007)(4326008)(786003)(43740500002)(45980500001);
	DIR:OUT; SFP:1102;
X-MS-Exchange-AntiSpam-MessageData-ChunkCount:	1
X-MS-Exchange-AntiSpam-MessageData-0:	=?utf-8?B?Wk9SRlBQcktUcXhBczFlZ0E1NXIxTzBEY3hVSGQ1eWhZMlR0SytQRWFjc1pE?=
	=?utf-8?B?TnZoTGtNb2pSQzdqZjJpK0UvdGRBS01CYVN0S3FZS1lKenVnUmFGenRxeExu?=
	=?utf-8?B?Zi9VUlhvdENndGhEd2R3OTAwNXpkKzUrbG1NNTgxU0VXVko5YWM4ak90ejVH?=
	=?utf-8?B?Wlh3UTdjSFFPZzd1eWtrUVVYNXBDc09sK203Q1lqeExVUSt1Z3NjNnJ0MnBB?=
	=?utf-8?B?ZFRENlN3V0czS2E0MUtaT3JCTlFNTnVBeUt0cTlJUGlPdlp5RmFmRGtiVnAr?=
	=?utf-8?B?Wm9kK3dUMkdTdkwzUlh2RkN6WDF0c2pRYUVTNm9LdjJDRUk5eEtudmxpYWdr?=
	=?utf-8?B?RWFqckpVMkJSK3VPNDFySWFMbWl4ZU5PZWE0ZDFTYkp2SElWTTh4TTExWkMv?=
	=?utf-8?B?UElGcURXcy94amxCTGozR3JSL2V5RGIxUGR6ZGRWdmh1SlNHU21ZTkw4bzJC?=
	=?utf-8?B?SEtDV2lZbzNXNjZVVlRKb1I3dEE3Y3BYalpFRUtwVGVZdGNsQjNYWEVqaEdk?=
	=?utf-8?B?YnJjQTlUZDNvN3FFV2kzbkRPM09MUWJzZnE0SlJVZ0M1aDladlZUOUlSZXNE?=
	=?utf-8?B?N2ZUT2IycUV3SmhnRXdGUTcvMGppamQ3c24reDhRbDVkdFpsQ0VrTnNvcXdl?=
	=?utf-8?B?SGMzSURXMVlpaHgxekZhV0RMR2txZFhOMHB5RW5ZZDZ4QkJBV1FCWGxWd1Ft?=
	=?utf-8?B?TzlyZFlGZlZ3OG1jT0dLL2dzU1dmVmtQRW9FanpFRGM4WGtTY3JwbDFKMEdH?=
	=?utf-8?B?NU1MdnEvNExKN1p3OS9uaGhucmRGbGs5TU1YeW1uaUwyTzBZanJidGh5ZGUx?=
	=?utf-8?B?U2xxYlRUV0Y0VGZBN3RiTWJKNGpGcURyMHNpT0cwODBpcDkzVWl2VEE5Zys3?=
	=?utf-8?B?Ky9jUDBvK0VyWVRLcFpnQ283WmVwWTViQ1BsNWorQ3R1WUxDeGc1ZzVzLzVH?=
	=?utf-8?B?dTJFTjlNeDRpZ3hMQlozdU5SZjVDTlpCZVduSDVHdEE5blM1Z1FKN1BZSzJk?=
	=?utf-8?B?RVhPQndZRk1KdmNtdW42ZitRaVBVVUlKRThRNjBkYTBFRXdMdkFOMWxlOEFG?=
	=?utf-8?B?MnUzbFFSRWlKaXFLanZqUFhkejI4Qm56eERPVEViNFprTWU2SFdDT05oQXpk?=
	=?utf-8?B?UU41WVBYN1V3NCs3a0hGSXdOWklSTytweVdyTzdUd1daWnlFa0I1a2c4YmMz?=
	=?utf-8?B?cjBJOFphbXprTWd5c2pZTWI1aC94RnUvSDFVcGxsUllmN0hZdG84Qng0a1FJ?=
	=?utf-8?B?a0ZHd3RpMDlnR3FUWHBhRGlhdnNITjdiUUMvUHp6bi82RTA0bTlPcmdhekVj?=
	=?utf-8?B?eHRsTDZvK2o0THFrNXdBL2kzQjRNTjhoa1EzcGxhUDVwRFUyRTdsTUx5elcr?=
	=?utf-8?B?emlNZ1hyRi9vWlhGLzJUZU96YnBwWWtOUTdyelFleUxxanlMZXZIa0d4Q01R?=
	=?utf-8?B?NlpLSnVBaEd0TEhEaWpybmxFMXJuZVdFbUtUTVB2ZFlENVVORnMwTUNxYUhR?=
	=?utf-8?B?K04wRS9HL1dMWCtzM0ZYNU5iTzUzTnk5cVc2VmZkT0szOWd3ZXpTbzFiamRk?=
	=?utf-8?B?clJqMXFmTVA4Y3hVZklyZXIxbnIyVVdQUnN1THI5R1Zpb2Q1YTlGQmlSdUFo?=
	=?utf-8?B?dmY4dWNDVEhsb0gra2Mxa1BINGIwREgxMCtaZ0l5U0EwQUhFalVCR0hPWUZh?=
	=?utf-8?B?cm1MZDN6dXhqTHNMWjMvaHROTGFzc1BNWnRkY2ZUL2NMTGxGRUpkNGtHbGQx?=
	=?utf-8?B?OG9jWlczbTR2a0pmcW95ZmZ5VjY1VnlPZEM5UDRWVXd4ZDlqMm5GelFla01F?=
	=?utf-8?B?ZElwYUpjRnBrbm1TZjFqVjBMMCtDWXVvVjRxU1VWOGlpT3dTZDBaelRnelJh?=
	=?utf-8?B?ZVdWRVlMc2tINEZ4dEFpeUxRcHJkS1o1cWxFWFRFSno1RVdyYVRiQ3QzUmFq?=
	=?utf-8?B?UVltaGErYUpVTENwbkVFS212TnkvejIzN3FUVDZDQ01kai9PajFMZlVpR2x6?=
	=?utf-8?B?WFBFU3kwL1ZPUnNIVVd4T2xmNUh4Nm0vb3RvUUVXNmg3djAxQlVNZGxKVnVZ?=
	=?utf-8?B?U3dFMUVjT0RYSzZyNzVaeTlvWm5QOFZPeXRZUlM4Y1FrZ1hQdlVGZXVCUWsz?=
	=?utf-8?B?SjFNaWZQdi9hcVBrVStGN1V5a3lVN01LbTY4c1hBSnRnS1phN1Rsb0x5MnZp?=
	=?utf-8?B?RzhtQ0JiVWJRT2lIZHRvUEtHZTdoRnArMlZaSFJObFNzR3RjR3o2SzY5K25S?=
	=?utf-8?Q?1F1MG+ymv+rMNKch/p5IzL+iaZ1A5XaadZJHFZvKOQ=3D?=
X-OriginatorOrg:	cornell.edu
X-MS-Exchange-CrossTenant-Network-Message-Id:	b76e0ed2-7ddb-47de-4089-08d9a4745b87
X-MS-Exchange-CrossTenant-AuthSource:	BN7PR04MB4388.namprd04.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs:	Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime:	10 Nov 2021 18:03:11.0516 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader:	Hosted
X-MS-Exchange-CrossTenant-Id:	5d7e4366-1b9b-45cf-8e79-b14b27df46e1
X-MS-Exchange-CrossTenant-MailboxType:	HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName:	WgBxL6jjLApafDPNlUx9M0CvhkWX3ylKs0etnfIjmIFtuO37ON/B8YpaeWuxn7D6wF+Y9h6NNU24g+xUs0XH0w==
X-MS-Exchange-Transport-CrossTenantHeadersStamped:	BN8PR04MB5617
X-Spam-Status:	No, score=-4.3 required=5.0 tests=BAYES_00, DKIM_SIGNED,
	DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, MSGID_FROM_MTA_HEADER, NICE_REPLY_A,
	RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2, SPF_HELO_PASS, SPF_PASS,
	TXREP autolearn=ham autolearn_force=no version=3.4.4
X-Spam-Checker-Version:	SpamAssassin 3.4.4 (2020-01-24) on
	server2.sourceware.org
X-BeenThere:	cygwin AT cygwin DOT com
X-Mailman-Version:	2.1.29
List-Id:	General Cygwin discussions and problem reports <cygwin.cygwin.com>
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:	Ken Brown via Cygwin <cygwin AT cygwin DOT com>
Reply-To:	Ken Brown <kbrown AT cornell DOT edu>
Cc:	cygwin AT cygwin DOT com
Sender:	"Cygwin" <cygwin-bounces+archive-cygwin=delorie DOT com AT cygwin DOT com>

On 11/10/2021 12:23 PM, Henry S. Thompson wrote:
> Ken Brown via Cygwin writes:
> 
>> On 11/9/2021 9:53 PM, Ken Brown via Cygwin wrote:
>>> Back to the drawing board.
>>
>> It finally occurred to me to stop looking for a bug in
>> fhandler_pipe::raw_read and instead see if something is in fact
>> repeatedly writing to the pipe, so that drain_signal_event_pipe
>> never finishes.  Putting a breakpoint at fhandler_pipe::raw_write, I
>> found that this is in fact the case.  While the main thread is
>> repeatedly reading from the pipe, a second thread is repeatedly
>> writing to it.  Here's the backtrace of that thread:
> 
> Argh.  Thanks for the hard labour on this.  This is not a part of the
> XEmacs code I have any experience of.  Is there any clue you can give
> about how things changed in all the September commits to
> fhandler_pipe.cc that might have exposed the XEmacs bug?

The main change was that we stopped using Win32 Overlapped I/O 
(https://docs.microsoft.com/en-us/windows/win32/sync/synchronization-and-overlapped-input-and-output) 
and switched to using the NT API.  As a result, pipe I/O became much more 
efficient.  It wouldn't surprise me if the efficiency alone is what exposed the bug.

The good news is that the bug doesn't seem to occur in XEmacs 21.4 (on 32-bit 
Cygwin).  So one way to approach this would be to bisect the XEmacs git repo to 
find the commit that introduced the bug.  You'd probably have to do the work on 
32-bit Cygwin since, if I remember correctly, XEmacs 21.4 didn't build on 64-bit 
Cygwin.

Ken

-- 
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 -