From owner-freebsd-java@FreeBSD.ORG  Fri Jan 18 01:43:02 2008
Return-Path: <owner-freebsd-java@FreeBSD.ORG>
Delivered-To: java@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id DA7D216A4C9
	for <java@freebsd.org>; Fri, 18 Jan 2008 01:43:02 +0000 (UTC)
	(envelope-from julian@elischer.org)
Received: from outS.internet-mail-service.net (outS.internet-mail-service.net
	[216.240.47.242])
	by mx1.freebsd.org (Postfix) with ESMTP id 5025113C474
	for <java@freebsd.org>; Fri, 18 Jan 2008 01:43:02 +0000 (UTC)
	(envelope-from julian@elischer.org)
Received: from mx0.idiom.com (HELO idiom.com) (216.240.32.160)
	by out.internet-mail-service.net (qpsmtpd/0.40) with ESMTP;
	Thu, 17 Jan 2008 17:43:01 -0800
Received: from julian-mac.elischer.org (localhost [127.0.0.1])
	by idiom.com (Postfix) with ESMTP id AB786126F66;
	Thu, 17 Jan 2008 17:43:00 -0800 (PST)
Message-ID: <47900422.9050905@elischer.org>
Date: Thu, 17 Jan 2008 17:42:58 -0800
From: Julian Elischer <julian@elischer.org>
User-Agent: Thunderbird 2.0.0.9 (Macintosh/20071031)
MIME-Version: 1.0
To: Landon Fuller <landonf@threerings.net>
References: <200711301716.lAUHGEV1064334@repoman.freebsd.org>
	<wpprxrto0s.fsf@heho.snv.jussieu.fr>
	<Pine.GSO.4.64.0711301659060.5465@sea.ntplx.net>
	<wpwsrz9uyr.fsf@heho.snv.jussieu.fr>
	<Pine.GSO.4.64.0711301849310.6581@sea.ntplx.net>
	<wphcj2plsx.fsf@heho.snv.jussieu.fr>
	<Pine.GSO.4.64.0712011824130.11446@sea.ntplx.net>
	<wphcj1dmvz.fsf@heho.snv.jussieu.fr>
	<90584F61-91FE-446E-978E-FD234553E8FC@threerings.net>
	<478FFC91.4050508@elischer.org>
	<4E316E30-3A6B-4E58-A701-E85389BEC6EE@threerings.net>
	<478FFF09.7020207@elischer.org>
In-Reply-To: <478FFF09.7020207@elischer.org>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Cc: nate@yogotech.com, ivo@scito.com, Alfred Perlstein <alfred@freebsd.org>,
	Daniel Eischen <deischen@freebsd.org>, davidxu@freebsd.org,
	java@freebsd.org, julian@freebsd.org
Subject: Re: cvs commit: src/lib/libkse/thread thr_kern.c
X-BeenThere: freebsd-java@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Porting Java to FreeBSD <freebsd-java.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-java>,
	<mailto:freebsd-java-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-java>
List-Post: <mailto:freebsd-java@freebsd.org>
List-Help: <mailto:freebsd-java-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-java>,
	<mailto:freebsd-java-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 18 Jan 2008 01:43:02 -0000

Julian Elischer wrote:
> Landon Fuller wrote:
>>
>> On Jan 17, 2008, at 17:10, Julian Elischer wrote:
>>
>>> I gather it is the PARENT that hangs here?
>>>
>>
>> Parent continues, the child hangs in fork().
> 
> no the child hangs in mutex_lock_common()
> 
> please do a ktrace of the program and send that to me
> 
Here's my guess as to what is happening:
thos is not based on code..

thread 1 calls the dummy fork(3)
thread 2 calls the dummy fork(3)
thread 1 calls fork(2), (the syscall, from within the dummy fork)
thread2 calls fork(2) (the real one in the kernel)
      thread 1 proceeds
      thread 2 blocks on a VM lock until thread 1 completes
      kernel duplicates the memory space
thread 1 returns from fork(2)
thread 1 takes out mutex X inside dummy fork(3)
      thread 2 proceeeds in the kernel on forking.
      kernel duplicates the memory space (including mutex X)
thread 2 returns from kernel and looks for mutex X
thread 2 in client tries to take out mutex X inside dummy fork(3) and 
waits.
thread 1 releases mutex X
thread 2 proceeeds
================================
in child1 thread1 runs fine.
in child2 thread2 waits for thread 1 to drop the mutex
  (there is no thread1)


the question is: what is the mutex being acquired AFTER forking?

Dan?