LiveCode 6.6 Screen Freeze Bug

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mickpitkin92
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LiveCode 6.6 Screen Freeze Bug

Post by mickpitkin92 » Wed Mar 26, 2014 6:41 pm

Hey guys, I've upgraded to 6.6 the other week and have noticed one really annoying bug and it happens randomly for me and is really awkward to reproduce as I don't know how to trigger the symptoms effectively but basically it goes like this, I get an average of about half an hours use out of 6.6's IDE and then the screen starts to lock up, basically the IDE appears to be active but refuses to update the actual window contents.

Additionally the window will refuse to activate when clicked but will activate when the button in the taskbar is clicked which will allow me to press Ctrl+S to save but then I usually have to blind type Ctrl+M and then Quit to shutdown the IDE or Task Manager it out of existence, it doesn't stop responding as Windows doesn't ghost the window image and as made evident by the fact that I can blind type Quit and the engine will shutdown.

Again it is hard to reproduce as I don't know the exact method of reproducing the symptoms just that they are as described above, the bug doesn't appear in 6.5 and earlier and honestly sounds like a jam in the message pump that redraws the contents of the window but if memory serves that would cause Windows to ghost the windows and state it is not responding so if anyone else has experienced this or a developer could chime in, I'm hoping we can track this down and fix it for a maintenance release.

Best wishes, Mich.

EDIT: Forgot to mention, when the bug does occur, the taskbar gets a slight glitch where a chunk of the button representing the LiveCode's menubar window shows right in the corner, additionally the Hot Corner to activate the last used Metro app stops showing and the Taskbar right click menu no longer shows if you right click. Again its strange to me.
Currently working on the Nix Operating System, an operating system that runs atop of Windows and Mac with the goal of providing an alternative to those systems without having to leave them whilst providing the features of a standard OS.

paul_gr
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Re: LiveCode 6.6 Screen Freeze Bug

Post by paul_gr » Wed Mar 26, 2014 7:18 pm

Hi Mich,
Sounds similar to this thread --
LC 6.6 IDE keeps locking up at irregular intervals Win 8
http://forums.runrev.com/phpBB2/viewtop ... =9&t=19734

Paul

mickpitkin92
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Re: LiveCode 6.6 Screen Freeze Bug

Post by mickpitkin92 » Wed Mar 26, 2014 8:04 pm

That sounds exactly like the symptoms I've been having, the final post of the topic states that it seems to occur in the standalone engine as well as the dev engine so I'm thinking (And this is a theory) that LiveCode is encountering a deadlock when updating a graphics queue to pass to Windows with the information about objects on the screen, if memory serves Windows utilizes two message queues, one is the standard Win32 message queue for receiving window messages basically WM_CLOSE, etc. get sent through this queue and then there is a second queue for the application to update the display of its window(s) on screen.

When this queue is updated it will either get sent through to the DWM.EXE process to be drawn whilst Windows Aero is active or sent straight to the window manager, either option is transparent and I think LiveCode is possibly deadlocking when updating this queue, again its a theory but it would explain the screen freeze even though the application is otherwise still running, so I'm thinking the deadlock is caused by a possible race condition, a developer will have to chime in but that's what I'm putting my money on.
Currently working on the Nix Operating System, an operating system that runs atop of Windows and Mac with the goal of providing an alternative to those systems without having to leave them whilst providing the features of a standard OS.

livecodeian
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Re: LiveCode 6.6 Screen Freeze Bug

Post by livecodeian » Mon Apr 07, 2014 11:34 am

Hi guys, the cause of this bug (bug no 12010 in the QA centre) has been identified and fixed in 6.6.1-rc1.

Ian.

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