From owner-freebsd-threads@FreeBSD.ORG  Thu Jul 14 16:25:24 2005
Return-Path: <owner-freebsd-threads@FreeBSD.ORG>
X-Original-To: freebsd-threads@freebsd.org
Delivered-To: freebsd-threads@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id E2ACE16A41C
	for <freebsd-threads@freebsd.org>; Thu, 14 Jul 2005 16:25:24 +0000 (GMT)
	(envelope-from ghelmer@palisadesys.com)
Received: from magellan.palisadesys.com (magellan.palisadesys.com
	[192.188.162.211])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 932C443D45
	for <freebsd-threads@freebsd.org>; Thu, 14 Jul 2005 16:25:24 +0000 (GMT)
	(envelope-from ghelmer@palisadesys.com)
Received: from [172.16.1.108] (cetus.palisadesys.com [192.188.162.7])
	(authenticated bits=0)
	by magellan.palisadesys.com (8.12.11/8.12.11) with ESMTP id
	j6EGPMcM026234
	(version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO)
	for <freebsd-threads@freebsd.org>; Thu, 14 Jul 2005 11:25:22 -0500 (CDT)
	(envelope-from ghelmer@palisadesys.com)
Message-ID: <42D691F2.3030201@palisadesys.com>
Date: Thu, 14 Jul 2005 11:25:22 -0500
From: Guy Helmer <ghelmer@palisadesys.com>
User-Agent: Mozilla Thunderbird 1.0.2 (Windows/20050317)
X-Accept-Language: en-us, en
MIME-Version: 1.0
To: freebsd-threads@freebsd.org
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
X-Palisade-MailScanner-Information: Please contact the ISP for more information
X-Palisade-MailScanner: Found to be clean
X-MailScanner-From: ghelmer@palisadesys.com
Subject: system scope threads entering STOP state
X-BeenThere: freebsd-threads@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Threading on FreeBSD <freebsd-threads.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-threads>, 
	<mailto:freebsd-threads-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-threads>
List-Post: <mailto:freebsd-threads@freebsd.org>
List-Help: <mailto:freebsd-threads-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-threads>,
	<mailto:freebsd-threads-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 14 Jul 2005 16:25:25 -0000

I have a long-running multithreaded process on FreeBSD 5.4 (SMP, 
PREEMTPION, SCHED_4BSD) linked with libpthread and I'm creating the 
threads with attribute PTHREAD_SCOPE_SYSTEM.  The threads need to be 
processing input in near-real-time or its input buffers overflow.

I've modified the program so that a thread can fork/execl/waitpid 
(without WNOHANG) to use an external program for further processing on a 
batch of input (sometimes via a pipe, other times via writing to a 
file).  However, even under a light input load, the program is now 
dropping input.  While running top(1) in thread mode, I occasionally 
find all the program's threads are in the STOP state for several 
consecutive seconds.  Is there anything related to the frequent use of 
fork, execve, or wait4 that would be likely to cause such a situation?  
I'm not seeing anything obvious in my reading of the kernel sources.

Thanks in advance for any help,
Guy

-- 
Guy Helmer, Ph.D.
Principal System Architect
Palisade Systems, Inc.