[Vm-dev] OSProcessPlugin: VMConstruction-Plugins-OSProcessPlugin.oscog-eem.41.mcz

David T. Lewis lewis at mail.msen.com
Tue Jan 22 03:47:42 UTC 2013


These commit notices are repeats from a bunch of earlier postings.
SqueakSource was down for some reason, and I suspect that something was
done during the restart to cause a bunch of commit notices to be resent.

Eliot did make some changes to the OSPP signal handling to use an alternate
signal stack. This prevents stack overflows that can affect a stack interpreter
(Cog) if a signal handler consumes more stack space than expected.

So yes the changes are intended to prevent stack overflow corruption that
could happen when signals are being handled, and yes OSProcess does a lot
of signal handling. I don't know how or if the stack issues might relate
to becomeForward:, but I do know that (for all sorts of problems of this
nature) any sort of object memory corruption caused by one bug is likely
to show up as a crash later on during memory traversal, so maybe they
are indirectly related.

I'm not sure the versions in which these changes took effect (2672, 2673?).


On Mon, Jan 21, 2013 at 12:03:18PM -0600, Chris Muller wrote:
> Hi Eliot, I just wanted to confirm whether these changes are intended
> to address crashing issues of the new 2673 VM.  I was happy to read
> your release notes of 2673 because they seem to indicate you're aware
> of an issue I experience related to use of bulk becomeForward: -- as
> if not all are getting becomed.  However I went back to 2672 for now
> because 2673 crashes very quickly during OSProcess activity.
> Thanks.
> On Sun, Jan 20, 2013 at 1:23 PM,
> <squeak-dev-noreply at lists.squeakfoundation.org> wrote:
> >
> > Eliot Miranda uploaded a new version of VMConstruction-Plugins-OSProcessPlugin to project OSProcessPlugin:
> > http://www.squeaksource.com/OSProcessPlugin/VMConstruction-Plugins-OSProcessPlugin.oscog-eem.41.mcz
> >
> > ==================== Summary ====================
> >
> > Name: VMConstruction-Plugins-OSProcessPlugin.oscog-eem.41
> > Author: eem
> > Time: 14 December 2012, 4:42:40 am
> > UUID: 0406d3fc-7b8b-4b72-b20a-f254eeb1b893
> > Ancestors: VMConstruction-Plugins-OSProcessPlugin.oscog-eem.40
> >
> > Check for needing sigaltstack properly in setSignalNumber:handler:
> >

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