[Vm-dev] Frequent SegFaults in PharoVM with Pharo 3.0

[Max Leske]

On 07.11.2013, at 00:27, vm-dev-request at lists.squeakfoundation.org wrote:

> Date: Wed, 6 Nov 2013 19:23:47 -0200
> From: Mariano Martinez Peck <marianopeck at gmail.com>
> Subject: Re: [Vm-dev] Frequent SegFaults in PharoVM with Pharo 3.0
> To: Squeak Virtual Machine Development Discussion
> 	<vm-dev at lists.squeakfoundation.org>
> Message-ID:
> 	<CAA+-=mWDtHGQWSHx-m4u37Kj0UAMx=UG=qUCz+wMvgDT8BaQZQ at mail.gmail.com>
> Content-Type: text/plain; charset="windows-1252"
> 
> Max, did you try with Eliot VMs besides the pharo ones?

No, I haven’t. I can try (though only on my machine), but if I can’t reproduce the SegFault that doesn’t mean much unfortunately. It took me 10 to 20 tries with the PharoVM too…

I’ll try anyway and let you know what I find.

Max

> 
> Thanks
> 
> 
> On Wed, Nov 6, 2013 at 6:04 PM, Max Leske <maxleske at gmail.com> wrote:
> 
>> 
>> Hi
>> 
>> We’ve been encountering frequent SegFaults when running the Fuel tests on
>> the Pharo CI (https://ci.inria.fr/pharo-contribution/job/Fuel/). Since
>> today I’ve also been able to reproduce the SegFaults on my MacBook Pro (OS
>> X 10.9) too. We have not been able to determine the cause of the SegFault
>> but we can produce SegFaults often, although not reliable (more reliable on
>> the CI).
>> 
>> The CI uses the stable VM:
>> http://files.pharo.org/vm/pharo/linux/stable.zip
>> I use a newer version from October on my machine:
>> http://files.pharo.org/vm/pharo/mac/273.zip
>> 
>> I’ve attached all the dumps of the crashes I was able to produce on my
>> machine, together with Apple’s crash logs.
>> 
>> I’ve been able to deduce the following:
>> - garbage collection seems to be a trigger for the SegFault. When one of
>> the methods FLMethodContextSerialization>>testFuelShouldIgnoreFuel and
>> FLMethodContextSerialization>>testMethodContextWithNilPc contain the line
>> “3 timesRepeat: [Smalltalk garbageCollect]” the SegFault appears nearly
>> always (on CI). When I remove the line the builds run through.
>> - Not all methods with the garbage collect line trigger a SegFault (I
>> could only identify those two)
>> - the garbage collect line itself suffices as a trigger in the mentioned
>> methods.
>> - The number of tests (amount of used memory?) seems to influence the
>> appearence of the SegFault (e.g. loading "DevelopmentGroup" seems to
>> trigger it more often than loading “Benchmarks”)
>> - the SegFault always appears after the tests with the garbage collect
>> line have been run, never before
>> - the VM can’t write the crash.dmp every time
>> 
>> Since the SegFaults are so random I cannot give you an image to reproduce
>> the problem. I’ve had the best results using a fresh 3.0 image (
>> http://files.pharo.org/image/30/30549.zip) and then evaluating the
>> following in a workspace:
>> 
>> Gofer it
>>        smalltalkhubUser: 'Pharo' project:  'Fuel';
>>        package: 'ConfigurationOfFuel';
>>        load.
>> 
>> ((Smalltalk at: #ConfigurationOfFuel) project version: #bleedingEdge)
>> load: 'DevelopmentGroup'.
>> 
>> HDTestReport
>>        runClasses: (TestCase allSubclasses select: [ :class | class name
>> beginsWith: 'FL'])
>>        named: ‘foo'
>> 
>> If it doesn’t work, try using the TestRunner manually. Select the default
>> Fuel tests (alphabetically at F) and the additional Fuel tests (at the
>> bottom of the list) and run them.
>> 
>> If anybody has any clue about what could be going on I’d really appreciate
>> any input. I’ll happily provide more information if I can.
>> 
>> Thanks for reading :)
>> Max
>> 
>> 
>> 
> 
> 
> -- 
> Mariano
> http://marianopeck.wordpress.com

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