On Tue, Apr 28, 2009 at 09:40:14AM -0700, Alan Irwin wrote:
> On 2009-04-28 10:45+0100 Andrew Ross wrote:
>
>> [...]I've been using HAVE_PTHREAD=ON for a long time with the xwin driver
>> with no
>> problems. It has certainly been enabled in the debian packages as well with
>> no reported bugs. Based on this I am relatively sure that this bit is ok. The
>> problem is that there is some extra code for handling user supplied windows
>> which is currently only exercised by plframe. I suspect the error is there.
>> Based on this I would like to propose that we disable HAVE_PTHREAD for
>> plframe,
>> but not more generally. We could do this by ensuring that -drvopt
>> usepthread=0
>> is set in the plframe code.
>>
>> This would mean users don't have to choose between losing very useful
>> functionality with xwin and potentially having a bug in the tk code. I think
>> this
>> is particularly important as the xwin driver is I imagine much more widely
>> used
>> that the tk code. Does this sound acceptable to everyone?
>
> Hi Andrew:
>
> You may recall that the lost text problem for -dev xcairo windows resizing
> was spread by HAVE_PTHREAD=ON to the case where even the window focus was
> being changed. I now assume that was just HAVE_PTHREAD=ON doing its job
> since I just checked that Hazen's recent fix for the lost text -dev xcairo
> issue also works fine for the HAVE_PTHREAD=ON case. Thus, your suggested
> much more minor workaround of simply turning HAVE_PTHREAD OFF just for the
> Tk case rather than in general is fine by me.
I tried this but it produces a rather curious result. I added a call to
plsetopt("drvopt","usepth=0") in plframe.c just before the call to
plsdev("xwin").
Adding printfs into drivers/xwin.c shows that this really does result in
usepthreads being set to 0. All the pthread specific code is wrapped in
"if (usepthreads)" statements. Suprisingly the segmentation faults still occur
even in this case. Only setting HAVE_PTHREADS=OFF seems to cure the problem.
This is a rather surprising result. As far as I can see this only leaves two
possibilities
1) Something in the headers included in the pthreads case is upsetting things
2) Some different link options are used if HAVE_PTHREADS=ON.
Anyway, this narrows down the possibilities a lot.
Andrew
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