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Subject: RE: G++ guru's please comment - Re: FW: pthread_create problem in Cygwin 1.1.8-2]
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Date: Mon, 9 Apr 2001 09:38:57 +1000
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Thread-Topic: G++ guru's please comment - Re: FW: pthread_create problem in Cygwin 1.1.8-2]
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From: "Robert Collins" <robert DOT collins AT itdomain DOT com DOT au>
To: <cygwin AT cygwin DOT com>
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> -----Original Message-----
> From: Christopher Faylor [mailto:cgf AT redhat DOT com]
> Sent: Monday, April 09, 2001 9:35 AM
> To: cygwin AT cygwin DOT com
> Subject: Re: G++ guru's please comment - Re: FW: 
> pthread_create problem
> in Cygwin 1.1.8-2]
> 
> 
> On Mon, Apr 09, 2001 at 07:21:09AM +1000, Robert Collins wrote:
> >----- Original Message -----
> >From: "Joost Kraaijeveld" <J DOT Kraaijeveld AT Askesis DOT nl>
> >
> >>>1) It's possible it's a problem with the thread exiting 
> code, could you
> >>>try using a pthread_exit call instead of return and report back.
> >>I replaced return 0 with pthread_exit(0) andf now id does 
> not crash on
> >>any computer.
> >
> >hmm.  This really needs a compiler expert to jump in and comment now
> >(that reduces the likelyhood that it's a thread specific fault.
> 
> It's not likely that it is a compiler problem.  pthread_create calls
> __pthread_create which calls the user function.  If the user function
> returns it should it a __pthread_exit.  If it doesn't hit the
> __pthread_exit, then that would mean that the stack is corrupted
> somehow.
> 
> That should be pretty simple to debug.

It should be, so I did. I haven't got a working binary to compare with
(Earnie: please mail me your working one, with symbols.) I think it's a
problem in static code so I should be able to see the difference..

Background: pthread_create starts the new thread with a wrapper
function. The wrapper function runs the thread function, and when the
user function returns then cleans up the unix structures and calls
ExitThread(0); The crash occurs _before_ control returns to the wrapper
function. This implies it's a problem in the return code.

Other things we know: the return in the try{} is at fault. Returning
outside the try{} works ok. Calling pthread_exit directly works ok.

I can't see any syncronisation issues with the source that Joost
provided.

In short I think this is a 2.95.3 g++ problem.

> 
> >>> 2) What cygwin1.dll are you using? I'm using a custom 
> build ~= to the
> >> > latest snapshot.
> >> $ uname -a
> >> CYGWIN_NT-5.0 ABRARACOURCIX 1.1.8(0.34/3/2) 2001-01-31 
> 10:08 i686 unknown
> 
> i.e., not a snapshot.
> 
> cgf

Which is interesting: I see the behaviour with my threads code, and so
does Joost, but Earnie doesn't. Earnie is running gcc 2.95.2, Joost and
I are both running 2.95.3.

Rob

> 
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