X-Recipient: archive-cygwin AT delorie DOT com X-Spam-Check-By: sourceware.org Date: Tue, 3 May 2011 12:43:05 +0200 From: Corinna Vinschen To: cygwin AT cygwin DOT com Subject: Re: Two processes are always created while running cygwin program(bash, ls, etc) under windows 2003 x64 R2 Message-ID: <20110503104305.GF22745@calimero.vinschen.de> Reply-To: cygwin AT cygwin DOT com Mail-Followup-To: cygwin AT cygwin DOT com References: <210B64CF6061D847B4FE2374C8F37C6959DC652E58 AT GVW1160EXB DOT americas DOT hpqcorp DOT net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <210B64CF6061D847B4FE2374C8F37C6959DC652E58@GVW1160EXB.americas.hpqcorp.net> User-Agent: Mutt/1.5.21 (2010-09-15) Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner AT cygwin DOT com Mail-Followup-To: cygwin AT cygwin DOT com Delivered-To: mailing list cygwin AT cygwin DOT com On May 3 08:44, Oh, Choong-Hyun (HPSS-BSM) wrote: > Dear all, > > I found strange behavior of cywin application under windows 2003 x64 R2 version. > When I run bash, it creates parent bash process and also child bash process as like followings; > > > cmd.exe > +- bash.exe > +- bash.exe > > services.exe > +- cygrunsvr.exe > +- cygrunsvr.exe > > > But on Windows 2008 x64 R2 system, it create only one process as like followings; I assume you mean non-64 bit here. > cmd.exe > +- bash.exe > > services.exe > +- cygrunsvr.exe > > So I am wondering whether it is normal behavior of cygwin on Windows 2003 x64 R2 system or not. > And also if so, what's a cause of this happening. This happens if a Cygwin process (which is 32 bit and thus running in the WOW64 environment) is called from a 64 bit Windows process. On the older XP and 2003 64 bit systems, the first WOW64 processes main thread started from a 64 bit process gets a stack address in the range where usually the application itself resides. This in turn breaks Cygwin's fork. Therefore a Cygwin process checks at process startup if it has been started by a 64 bit parent process and if the stack address is in the dangerous region. If so, it re-spawns itself. Since this second process is started from another 32 bit process, its stack address is useful again. The intermediate process keeps in memory as long as the re-spawned process runs. Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Project Co-Leader cygwin AT cygwin DOT com Red Hat -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple