Wow! Wonderful experience report! Alexandre
> On Dec 19, 2016, at 2:03 PM, Peter Uhnak <[email protected]> wrote: > > On Mon, Dec 19, 2016 at 08:12:29AM +0800, Ben Coman wrote: >> Can yo point to where you added you workaround? > > The fix is a single line, because I hate myself. > > interpreterProxy failed ifTrue:[^nil]. > > https://github.com/pharo-project/pharo-vm/commit/9bf66cf656b176d988e1b0ba74fc37da467e6192 > > To give you more info: > > The problem is that memory of canvas forms are not properly pinned, so during > garbage collection the form is being moved, but if at the same time the > canvas form is being updated and moved, you are accessing wrong memory -> > crash. > > My fix will return prematurely if an error occurs and throws PrimitiveFailed > in the image before any wrong memory is accessed. On Roassal side the > PrimitiveFailed is catched and a paint cycle is skipped --- this is good > enough, as it results only in ocassional flicker that immediately fixes > itself instead of crashing the image. > > It seems that on Mac there are also other places in the BitBlt code where the > surface is being accessed without a check. > > Also be careful not to be misled by the crash dump stack. It took me quite a > while to figure out that GrafPort is already operating on wrong data, so it's > not GrafPort's fault, but BitBlt's; of course both should possibly be > investigated with respect to the mac crash. > > Final note, personally I found it much easier the debug and manipulate the > resulting C code (and recompiling just that), then to modify the Slang code > and rebuild the source code and recompile it all (but again, I don't know > what is the proper way to work with the VM code). > > I used this script to trigger the crash > https://gist.github.com/peteruhnak/024650ed2594301558df4da913549b54 > As the crash depends on memory consumption and "proper" garbage collection > cycle, it wasn't the easiest to reproduce, however the script above usually > managed to crash it. Having a more reliable way would be nice, but simply > triggering GC (nor full GC) wasn't enough because the memory wasn't in the > "right" state. > > Peter > _______________________________________________ > Moose-dev mailing list > [email protected] > https://www.list.inf.unibe.ch/listinfo/moose-dev -- _,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;: Alexandre Bergel http://www.bergel.eu ^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;.
