[Vm-dev] VM crash in the Squeak3D plugin

St├ęphane Rollandin lecteur at zogotounga.net
Sat Dec 28 18:20:22 UTC 2019

Hello all,

For my first post on this list, I would like to submit the bug that 
prevents one of my game (this one: 
http://www.zogotounga.net/comp/guardians.htm) to work reliably.

I spent quite some time on this, and I ended up with a nice and concise 
way to crash the Squeak3D plugin. The image is available at:


Instructions to crash the VM are detailed therein.

The 3D scene is very simple, there are only three objects. The crash
seems related to a race condition, because inserting a simple delay in
the code prevents it - this is detailed in the image itself.

I have spent days studying the Smalltalk code, and could not see
anything wrong with what is sent to the plugin. It looks to my
uninformed eyes as a problem of shared memory, where one rasterizing
operation messes up with another happening in parallel (although no
processed is being forked on the Smalltalk side).


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