[Vm-dev] Linux VM crash under memory pressure

David T. Lewis lewis at mail.msen.com
Sun May 20 17:35:55 UTC 2012

On Sun, May 20, 2012 at 03:08:20PM +0200, Bert Freudenberg wrote:
> Hilaire discovered that his newest DrGeo segfaults on the XO-1. It works fine elsewhere, including the XO-1.5, which has pretty much the same OS.
> We narrowed down the problem to the XO-1 having only 256 MB of RAM and no swap space. I can reproduce the crash in a virtual Ubuntu 12 with 768 MB RAM (!) but no swap. Top reports:
> Mem:    766204k total,   601588k used,   164616k free,    45624k buffers
> Swap:        0k total,        0k used,        0k free,   277024k cached
> but DrGeo still crashes. Etoys runs fine using the same Squeak VM on the same system (and on XO-1). DrGeo is based on Pharo 1.4, using a closure image. Etoys still is pre-closure. 

I recall some recent discussion on the Pharo list about some "strange objects"
that had entered the image for a period of time. It was something to do with
a mismatch in the number of instance variable slots. The VM crash is happening
in a method that is stepping through the fields of an object, so if something
was out of whack there it might well lead to problems.

The discussion started here:


It would be worth checking if the DrGeo image might have this issue, in
case those objects might for some reason be interacting badly with the
garbage collector.


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