[Vm-dev] [Pharo-dev] Random corrupted data when copying from very large byte array

Stuart Cassoff aa72 at bell.net
Tue Jan 23 15:15:19 UTC 2018


I'm curious to test both of these problems on obsd but don't know what to do to make the problem manifest itself, so if anyone could toss me a (preferably non-null) pointer, that'd be great.


Thanks,

Stu

> ---------- Original Message ----------
> From: Alistair Grant <akgrant0710 at gmail.com>
> Date: January 23, 2018 at 3:24 AM
> 
> 
>  
> Hi Eliot,
> 
> On 23 January 2018 at 01:47, Eliot Miranda <eliot.miranda at gmail.com> wrote:
> >
> > Hi Alistair,
> >
> > On Mon, Jan 22, 2018 at 1:42 AM, Alistair Grant <akgrant0710 at gmail.com> wrote:
> >>
> >>
> >> Hi Eliot,
> >>
> >> On Sat, Jan 20, 2018 at 09:19:04AM +0100, Alistair Grant wrote:
> >> > Hi Eliot,
> >> >
> >> > On 19 January 2018 at 23:04, Eliot Miranda <eliot.miranda at gmail.com> wrote:
> >> > > Hi Alistair, Hi Cl??ment,
> >> > >
> >> > > On Fri, Jan 19, 2018 at 12:53 PM, Alistair Grant <akgrant0710 at gmail.com>
> >> > > wrote:
> >> > >>
> >> > >> Hi Cl??ment,
> >> > >>
> >> > >> On 19 January 2018 at 17:21, Alistair Grant <akgrant0710 at gmail.com> wrote:
> >> > >> > Hi Cl??ment,
> >> > >> >
> >> > >> > On 19 January 2018 at 17:04, Cl??ment Bera <bera.clement at gmail.com>
> >> > >> > wrote:
> >> > >> >> Does not seem to be related to prim 105.
> >> > >> >>
> >> > >
> >> > >
> >> > > I suspect that the problem is the same compactor bug I've been trying to
> >> > > reproduce all week, and have just fixed.  Could you try and reproduce with a
> >> > > VM built from the latest commit?
> >> >
> >> > Happy to, but I'm out all day today, so it will be tomorrow or Monday.
> >> >
> >> > Cheers,
> >> > Alistair
> >> > (on the run...)
> >>
> >>
> >> I've tested this with 2 images and 3 VMs in all 6
> >> combinations:
> >>
> >> - "Old VM":   commit date: Wed Jan 10 23:39:30 2018 -0800, gcc 4.8.5
> >> - "New VM":   commit date: Sat Jan 20 13:52:26 2018 +0100, gcc 4.8.5
> >> - "GCC 5 VM": commit date: Sat Jan 20 13:52:26 2018 +0100, gcc 5.4.0
> >> - Clean image: commit id: b28d466f
> >> - Work image:  commit id: eb0a6fb1
> >>
> >> The gcc 5 is only there because I was playing with it.  The results may
> >> be useful, or completely misleading. :-)
> >>
> >> Each time I ran "5 timesRepeat: [ self test4 ]"
> >> with the halts replaced with a count increment.
> >> test4 is the method provided in Cyrille's original message.
> >>
> >> Result summary:
> >>
> >> - Old VM + Work image:  5, 5, 5, 0, 0
> >> - Old VM + Clean image: 5, 5, 0, 0, 0
> >> - New VM + Work image:  5, 0, 5, 5, 5
> >> - New VM + Clean image: 0, 0, 1, 5, 5
> >> - GCC 5 + Work image:   0, 0, 0, 0, 0
> >> - GCC 5 + Clean image:  0, 0, 0, 0, 0
> >
> >
> > This is strong evidence for the issue being a compiler bug with 4.8.x
> > If exactly the same input source for the Vm wrks with gcc 5 but not with 4.8.x then there is a small chance it is due to the Vm relying on undefined behavior, but I doubt it.
> > Assuming it is a gcc bug then
> > - it should be documented in the HowToBuild files for the relevant platforms
> > - Ci builds should start using gcc 5 and dispense with gcc 4.8.x
> > - since the problem is fixed with gcc 5 there seems little point trying to identify which version of gcc introduces the problem and communicating the problem to the gcc maintainers
> >
> > What's the status of the bug on Windows and Mac OS X?
> 
> 
> I can't check MacOS.  Clement?
> 
> I get the problem on Windows (version info below).
> 
> Note that Max Leske and I have been using gcc 4.8 because of a problem
> with OSProcess and gcc 5 (it possibly doesn't affect me anymore, I'm
> currently using OSSubprocess).  See:
> 
> http://lists.squeakfoundation.org/pipermail/vm-dev/2017-May/025216.html
> 
> I'll try and confirm correct OSSubprocess operation with gcc 5, but it
> will take a while, I'm battling too many different problems at the
> moment:
> 
> - TZ and DST handling on Windows
> - Windows VM suddenly can't find any of its plugins.  Is anyone else
> seeing strange behaviour here with VMs from the last few days?
> -- It looks like the plugin handling mechanism is completely different
> on Windows to Unix, so the VM doesn't report where it is looking and
> doesn't provide the option to specify the directory.  Grrrrrgh.
> - My linux build environment.
> - real life :-)
> 
> 
> Windows version info:
> 
> OS: Windows 10
> Image: Pharo 7.0 Build information:
> Pharo-7.0+alpha.build.439.sha.481071068244d0484241924f79ba791f80701316
> (32 Bit)
> VM:
> Win32 built on Nov 27 2017 00:05:44 GMT Compiler: 6.4.0 [Production Spur VM]
> CoInterpreter VMMaker.oscog- nice.2281 uuid:
> 4beeaee7-567e-1a4b-b0fb-bd95ce302516 Nov 27 2017
> StackToRegisterMappingCogit VMMaker.oscog-nice.2283 uuid:
> 2d20324d-a2ab-48d6-b0f6-9fc3d66899da Nov 27 2017
> VM: 201711262336 https://github.com/OpenSmalltalk/opensmalltalk-vm.git
> $ Date: Mon Nov 27 00:36:29 2017 +0100 $
> Plugins: 201711262336 https://github.com/OpenSmalltalk/opensmalltalk-vm.git $
> 
> 
> 
> 
> Cheers,
> Alistair


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