X-Recipient: archive-cygwin AT delorie DOT com
X-Original-To: cygwin AT cygwin DOT com
Delivered-To: cygwin AT cygwin DOT com
DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 6F3B8385840C
Authentication-Results: sourceware.org; dmarc=none (p=none dis=none)
 header.from=SystematicSw.ab.ca
Authentication-Results: sourceware.org;
 spf=none smtp.mailfrom=systematicsw.ab.ca
X-Authority-Analysis: v=2.4 cv=frTP2X0f c=1 sm=1 tr=0 ts=624f79ba
 a=oHm12aVswOWz6TMtn9zYKg==:117 a=oHm12aVswOWz6TMtn9zYKg==:17
 a=IkcTkHD0fZMA:10 a=uYT-Tk0qkVT609LjNaIA:9 a=QEXdDO2ut3YA:10
Message-ID: <23e627a3-39a7-e22f-6372-65d50f1a63d6@SystematicSw.ab.ca>
Date: Thu, 7 Apr 2022 17:54:33 -0600
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101
 Thunderbird/91.7.0
Subject: Re: Deadlock of the process tree when running make
Content-Language: en-CA
To: cygwin AT cygwin DOT com
References: <9388316255ada0e0fcb2d849cce5a894 AT ispras DOT ru>
From: Brian Inglis <Brian DOT Inglis AT SystematicSw DOT ab DOT ca>
Organization: Systematic Software
In-Reply-To: <9388316255ada0e0fcb2d849cce5a894@ispras.ru>
X-CMAE-Envelope: MS4xfPze1lCqUpLcuAwagiw4QNTtHC4GqYPPWc4XuFW+PAa/OnrLfRCDbam+l1cRM6G3abA+7z8pf3IsZBGRCRc9Moi/73iFg3Ms+eBJgPj/sBi36YgV7JDE
 CSAynVpG1U91mlGUaUfdsT9RK15EsLNDCJgALweU2RhvdKJ1W1ktzMMgE+/9xeO3cshTgAbyKqTirtk0bMei0pVPbWHwzdU3KycMAQp9226Q60eWmncb4cCs
X-Spam-Status: No, score=-1163.9 required=5.0 tests=BAYES_00, BODY_8BITS,
 KAM_DMARC_STATUS, KAM_LAZY_DOMAIN_SECURITY, NICE_REPLY_A, RCVD_IN_MSPIKE_H2,
 SPF_HELO_NONE, SPF_NONE, TXREP,
 T_SCC_BODY_TEXT_LINE 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
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>
Reply-To: cygwin AT cygwin DOT com
Cc: Alexey Izbyshev <izbyshev AT ispras DOT ru>
Content-Type: text/plain; charset="utf-8"; Format="flowed"
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 237NsrkM001569

On 2022-04-07 15:53, Alexey Izbyshev wrote:
> I'm using 32-bit Cygwin 3.3.4 on 64-bit Windows 10 21H2. When running 
> parallel make (for testing my project), very rarely I get the whole 
> process tree hanging at some seemingly random point. An example of such 
> a tree:
> 
> make-+-make-+-bash---find
>       |      |-bash---find
>       |      |-bash---find
>       |      |-bash---find
>       |      |-bash---find
>       |      `-bash---javac
>       `-make-+-bash---bash---bash---readlink
>              `-bash---bash---bash-+-grep
>                                   `-grep
> 
> (In the above tree, javac is the zombie parent of a native javac, and 
> the latter doesn't exist at this point).
> 
> I got such hang two times while running make in a loop for several days. 
> ProcessHacker shows that all leaf processes are single-threaded and are 
> stuck on WaitForSingleObject().
> 
> I've skimmed git log of cygwin-3_3-branch after cygwin-3_3_4-release, 
> but couldn't find anything that seems definitely related.
> 
> Has anybody seen something like this?
> 
> Is there any way I can get useful data for diagnosing this hang from the 
> process tree that I currently have hanging (I'm going to keep it for 
> now)? Otherwise, what would be the best strategy?

I've seen infinite loops with readlink in build scripts under Cygwin.
Seeing that readlink in a process tree makes me suspicious that 
something in a shell script is looping because two paths never match or 
always match under Cygwin.
Often there is one constant path and a varying path which is subjected 
to readlink in a loop.
Under Cygwin, you may have to pass the first path through readlink and 
compare that resulting path against the varying value.

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

This email may be disturbing to some readers as it contains
too much technical detail. Reader discretion is advised.
[Data in binary units and prefixes, physical quantities in SI.]

-- 
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