From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <zsh-workers-return-34548-mason-zsh=primenet.com.au@zsh.org>
Received: (qmail 9384 invoked by alias); 15 Feb 2015 18:21:08 -0000
Mailing-List: contact zsh-workers-help@zsh.org; run by ezmlm
Precedence: bulk
X-No-Archive: yes
List-Id: Zsh Workers List <zsh-workers.zsh.org>
List-Post: <mailto:zsh-workers@zsh.org>
List-Help: <mailto:zsh-workers-help@zsh.org>
X-Seq: 34548
Received: (qmail 13114 invoked from network); 15 Feb 2015 18:20:52 -0000
X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on f.primenet.com.au
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_NONE
	autolearn=ham version=3.3.2
X-Originating-IP: [86.6.153.127]
X-Spam: 0
X-Authority: v=2.1 cv=VLdTnr/X c=1 sm=1 tr=0 a=39NrsSuza2clQiZR/7fYWQ==:117
 a=39NrsSuza2clQiZR/7fYWQ==:17 a=kj9zAlcOel0A:10 a=NLZqzBF-AAAA:8
 a=pGLkceISAAAA:8 a=62SDsdWj0bbVUcv1TPgA:9 a=CjuIK1q_8ugA:10
Date: Sun, 15 Feb 2015 18:20:48 +0000
From: Peter Stephenson <p.w.stephenson@ntlworld.com>
To: Soares Chen <soares.chen@gmail.com>, zsh-workers@zsh.org
Subject: Re: Zsh scripts leave defunct processes when running under docker
 exec
Message-ID: <20150215182048.6ae1f637@ntlworld.com>
In-Reply-To: <CACUDQOHGXoOHLLrtYETuDYeAHzUq=B3LrpJ3bjj0Ge6hHGJMfw@mail.gmail.com>
References: <CACUDQOE1y34_b_OF8g4kf7JJisyBc0T5Chr_E8xkZiyO_kTRGQ@mail.gmail.com>
	<CAH+w=7YBD6ocsd6+PL-AgpkDt4-O2AHPQa06U2=b7s2LfeORQw@mail.gmail.com>
	<20150211101130.2ac4d9b5@pwslap01u.europe.root.pri>
	<150211081345.ZM17542@torch.brasslantern.com>
	<20150213103919.GD1848@tarsus.local2>
	<150214105834.ZM4462@torch.brasslantern.com>
	<CACUDQOHGXoOHLLrtYETuDYeAHzUq=B3LrpJ3bjj0Ge6hHGJMfw@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit

On Sun, 15 Feb 2015 22:03:05 +0800
Soares Chen <soares.chen@gmail.com> wrote:
> I have talked to people at Docker. From my understanding, Linux has a
> feature called subreaper that can take over the role of init and
> become the parent of orphaned descendant processes. In this case  on
> top of having different PID namespaces, `docker exec` is spawning a
> process called nsenter to act as the subreaper. It is responsible to
> reap defunct processes by handling SIGCHLD. With it being the
> subreaper, all orphaned/defunct processes are captured by nsenter
> instead of propogating to the actual init process inside the
> container.
> 
> So current Docker didn't handle SIGCHLD properly and therefore causing
> all orphaned processes to become defunct. It is probably not a problem
> of zsh, just that its way of implicitly exec and orphaning child
> processes in the final command causing this bug to become obvious in
> Docker.

Sounds entirely possible.  Thanks for tracking that down, it's very
useful to know.

pws