[PD-dev] 0.43 startup procedure and vwait WAS: [PATCH 06/10] fixed race-condition in the audio/midi API initialization

[Hans-Christoph Steiner]

On Jul 15, 2010, at 10:28 AM, IOhannes zmölnig wrote:

> On 07/15/2010 04:21 PM, Hans-Christoph Steiner wrote:
>
>>
>> The options are wait forever or have a timeout.  The vwait code  
>> provides
>> a timeout.  I am fine with having a long timeout for the conditions  
>> you
>> describe but it would be harmful to not have a timeout because then
>> you'll have a pd-gui process that is just sitting there waiting  
>> forever
>> for pd to show up whether or not if ever will.  As some point pd-gui
>> should tell you that its not likely to happen and just quit.
>
> my approrach was not to wait at all, and as soon as pd shows up
> dynamically incorporate the info.
> no timeout, no waiting, no deadlock no racecondition.

The vwait timeout would not be needed if we can rely on 'pd' to  
actually fully die when it exits/crashes.  On Mac OS X at least it is  
often doesn't completely crash and the process just sits there doing  
who knows what.  If this happens on startup, pd-gui's exec call will  
not return, and pdtk_pd_startup won't be called and pd-gui will just  
sit and wait forever, giving us a zombie pd-gui.  The vwait stuff  
wouldn't be needed if we can rely of pd to exit completely on all  
platforms.  Just removing the vwait stuff is just replacing one  
problem with another.

>>
>> For this reason, I think its a bad idea to get rid of the vwait  
>> code and
>> move stuff to pdtk_pd_startup.  If there are bugs with the vwait
>> approach, I'd be happy to fix them.  For what IOhannes describes  
>> here,
>> it sounds like the timeout just needs to be increased.  Perhaps there
>
> i experienced a race-condition! please do not fix race-conditions by
> increasing a timeout.
>
> fgmar
> IOhannes

Relax, no one is suggesting fixing a race condition with a timeout.   
Can you describe how to reproduce the race condition? What's actually  
racing? Did Miller's changes fix it?

.hc


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