AW: LC 8 Random crash with QT set the filename of player on OS X

[Tiemo Hollmann TB]

Hi Dar,

thank you for your notions.
I think it wasn't a real recursion, because of the user interaction in
between, but you pointed me into the right direction.
I now have changed one call of a command with a *send* in 1 milliseconds
instead of a direct call and now the error is gone. Though I don't
understand it totally what was going on, it seems to me that this "handler
loop" chocked itself somehow and got problems with the memory, like you
pointed out.
You saved my weekend :)
Tiemo


-----Ursprüngliche Nachricht-----
Von: use-livecode [mailto:use-livecode-bounces at lists.runrev.com] Im Auftrag
von Dar Scott
Gesendet: Donnerstag, 2. Juni 2016 17:18
An: How to use LiveCode <use-livecode at lists.runrev.com>
Betreff: Re: LC 8 Random crash with QT set the filename of player on OS X

I don't think I have a very good understanding of your "loop".  

You seem to have some sort of recursion that will cause your call stack to
grow and grow.  it looks as though 1 calls 2 which calls 1 which calls 2
which calls 1 which calls 2 which calls....

At some point anything you do should cause a stack overflow.  This normally
would create an error without a crash, but it might be that some operations
assume space and will crash.  

If you don't intend the recursion, you might be able to break out the
start-from-begining essentials of one command to be called by both commands.


I'm just guessing here; I don't have a good understanding of what you are
doing.  Since this runs fine on W10, I have a feeling that my guess is
goofy.  

Dar


> On Jun 2, 2016, at 8:38 AM, Tiemo Hollmann TB <toolbook at kestner.de> wrote:
> 
> Hello,
> 
> OS X 10.11.5, LC 8.0, IDE. Same program runs fine on Windows 10
> 
> I have a pretty nasty issue, where I am right now a bit clueless, in 
> which direction I have to search. I have set the dontuseQT of  player
"myPlayer"
> to false because I am using old QT videos, which can't be played with AVF.
> 
> In a *videoPlay* handler I *set* the filename of player "myPlayer" to 
> tVideoFile, which works fine in all situations and the video is played 
> afterwords fine.
> 
> Now I have a pretty deep structure of handlers, as a kind of a loop 
> with the modal userdialog and playing a video. The handler with the 
> sheet/modal stack waits for some user interactions, calls the 
> *videoPlay* handler and calls again the first handler, so that it 
> starts from beginning. In the
> *videoPlay* handler randomly this error occurs, when setting the 
> filename of the player object.
> 
> 
> 
> A simplified structure looks like this:
> 
> command1:
> 
> *modal* stack myDialog
> 
>                command2
> 
> 
> 
> command 2:
> 
>                *set* the filename of player -> error
> 
>                command1
> 
>                *modal*stack myDialog
> 
> 
> 
> 
> 
> I have already tried to set a *wait" with messages before the *set* 
> the filename, but it still crashes randomly.
> 
> As far as I can see, there are two main differences between the 
> handler, where the issue occurs and where not. 1. The deeper structure 
> of handlers and 2. The modal stack in between this handler "loop".
> 
> 
> 
> My feeling is that the engine choks somewhere in the "loop", but with 
> different handler calls with/without *send* / *dispatch* I would 
> probably mess up the "loop" structure.
> 
> 
> 
> Any idea, where to start?
> 
> Thanks
> 
> Tiemo
> 
> 
> 
> 
> 
> 
> 
> 
> 
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