On 15 Apr 2015, at 16:04, Jonathan Taylor <jonathan.tay...@glasgow.ac.uk> wrote: > I've started encountering intermittent problems in one specific window in my > application, where text input boxes become unresponsive, steppers remain > highlighted after clicking, etc. I'm rather short of ideas on how to debug > this, particular since I haven't worked out how to reproduce it reliably. > Other windows seem to remain unaffected. > > From dimly-remembered past experience I have a feeling it could be related to > something somewhere resulting in GUI code being executed on a non-main > thread. There is in principle a risk of that, since the window interacts with > peripherals/drivers etc involving multithreaded code. I've tried to isolate > the GUI code from the multithreaded code, but may perhaps have missed some > obscure case. [ideally, I'd probably totally isolate anything multithreaded > from ObjC code, but that would mean a proliferation of shadow classes, which > is something I'd prefer to avoid being dragged into] > > Even if my suspicion about the cause (multithreading+GUI) is correct, I'm > still not sure how to pin down and debug the problem, since there are so many > entry points into GUI-related code (e.g. property value changes), not all of > which even involve my own code directly. It would be great if there was some > way of enabling a global "exception if main-thread requirements are > violated", but I certainly haven't heard of such a thing (and can imagine > there could be very good reasons why it would be prohibitively hard to > implement). Can anyone suggest ways to diagnose and debug my problem (or > indeed suggest other possible causes I haven't thought of)?
A few ideas: - access of UI from non-main thread, corrupting data - view inserted as subview of one of its superviews - Someone calling one of the nextEventMatchingMask: methods and swallowing events that someone else is looking for to end a loop. - Exception thrown from tracking code - Someone calling display: from inside drawRect:, causing an endless recursion Have you tried just pausing your app in the debugger when this happens and looking at each thread to see what is running? Cheers, -- Uli _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
