X-Recipient: archive-cygwin@delorie.com X-Spam-Check-By: sourceware.org Date: Wed, 15 Jul 2009 14:56:36 -0400 From: Christopher Faylor To: cygwin@cygwin.com Subject: Re: perl threads on 2008 R2 64bit = crash ( was: perl 5.10 threads on 1.5.25 = instant crash ) Message-ID: <20090715185636.GA16211@ednor.casa.cgf.cx> Reply-To: cygwin@cygwin.com Mail-Followup-To: cygwin@cygwin.com References: <20090714205617.GA12534@ednor.casa.cgf.cx> <8541BCA91FF64580AA7A8065FBF9C938@multiplay.co.uk> <39B3B148DA514671BB2E1AE46946169C@multiplay.co.uk> <20090715000331.GA5635@ednor.casa.cgf.cx> <6D01817BC10A4430AFE7A590CC935C09@multiplay.co.uk> <20090715152139.GA694@calimero.vinschen.de> <4A5DFDDF.2000904@gmail.com> <20090715162243.GL14502@ednor.casa.cgf.cx> <4A5E0AB1.9020201@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A5E0AB1.9020201@gmail.com> User-Agent: Mutt/1.5.20 (2009-06-14) Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner@cygwin.com Mail-Followup-To: cygwin@cygwin.com Delivered-To: mailing list cygwin@cygwin.com On Wed, Jul 15, 2009 at 05:58:25PM +0100, Dave Korn wrote: >Christopher Faylor wrote: >> On Wed, Jul 15, 2009 at 05:03:43PM +0100, Dave Korn wrote: >>> Corinna Vinschen wrote: >>> >>>> What happens is that this statement >>>> >>>> if ((*object)->magic != magic) >>>> >>>> in the function thread.cc:verifyable_object_isvalid throws an exception >>>> because *object is NULL. This should be covered by the myfault handler >>>> in this function but for some reason it isn't. >>> So, set a "*object == 0" conditional breakpoint on that line and see what >>> the SEH chain looks like? >> >> But the point is that this shouldn't have caused a SEGV. > > Don't understand quite what you're alluding to. Where did Corinna refer to >a SEGV? Unless we're using the words differently, a SEGV is a signal, which >is a cygwin posix construct generated in response to an unhandled x86 access >violation exception. Corinna said that the call to v_o_i caused an >*exception*, as dereferencing a NULL pointer always does, and that it should >have been covered by the myfault handler (which as far as I know works by >wrapping an SEH handler around the block of protected code, and using it to >catch exceptions and longjmp back to the receiver) and which might lead to a >SEGV signal being generated somewhere a long way down the road if it failed to >catch the exception, but I'm just concentrating on the point of failure. >Hence my suggestion to breakpoint it just before the exception happens and see >what the state of the SEH chain looks like. The point is that this is generating the equivalent of a SEGV without ever hitting Cygwin's "SEH" code. Setting a breakpoint on the line would likely just show you the call stack but would not provide any insight into why the myfault was not invoked. cgf -- 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