thanks clement.
Max this is a nice catch.

Stef
On Nov 25, 2013, at 1:13 PM, Cl�ment Bera <bera.clement@gmail.com> wrote:

Hello,

In this version I added #timesRepeat: as a special selector to be inlined by the compiler (as #to:do:, #ifTrue:, ...). There was already another side effect of this addition of timesRepeat: as a special selector for XStreams. I guess we should remove it.

Try to edit the default Opal options in:
OpalCompiler>>#defaultOptions

instead of:
+ optionInlineTimesRepeat
put:
        - optionInlineTimesRepeat

Then execute: OpalCompiler recompileAll.
(If you run your code with a DoIt you do not need to recompileAll, but just in case ...)

And see if you bug comes from the timesRepeat:.

Now the bytecode for "3 timesRepeat: [ Smalltalk garbageCollect ]" is correct. But there may be some side effect in the VM I am not thinking of.

29 <20> pushConstant: 3
30 <68> popIntoTemp: 0
31 <10> pushTemp: 0
32 <76> pushConstant: 1
33 <69> popIntoTemp: 1
34 <11> pushTemp: 1
35 <10> pushTemp: 0
36 <B4> send: <=
37 <AC 09> jumpFalse: 48
39 <41> pushLit: Smalltalk
40 <D2> send: garbageCollect
41 <87> pop
42 <11> pushTemp: 1
43 <76> pushConstant: 1
44 <B0> send: +
45 <69> popIntoTemp: 1
46 <A3 F2> jumpTo: 34
48 <7C> returnTop



2013/11/25 Max Leske <maxleske@gmail.com>
I was able to isolate the image where the SegFault problem appears first: 30435. Here�s the update method:

update30435
"self new update30435"
self withUpdateLog: '11729 Sync Opa from repo: #timesRepeat optimization enabled
11720 DateModel: Add #displayBlock:
11727 remove unused ivar scrollBarOnLeft in ScrollPane
self loadTogether: self script114 merge: false.
(SystemNavigation new allCallsOn: #timesRepeat:) do: [ :each | each method recompile ].
self flushCaches.


What I noticed is that 11729 is about #timesRepeat: and the code I used to trigger the SegFaults is �3 timesRepeat: [ Smalltalk garbageCollect ]�. So the problem might actually lie in #timesRepeat: rather than in #garbageCollect:

@Marcus
I�ve put you into CC because I hope that you know more about #timesRepeat:

Cheers,
Max



On 25.11.2013, at 08:26, Max Leske <maxleske@gmail.com> wrote:

Interesting development: no SegFaults (while using exactly the same code) when using an older Pharo image (version 30321 instead of latest).
This obviously suggests that the problem lies with the image and not necessarily the vm.

Max

On 10.11.2013, at 20:10, Max Leske <maxleske@gmail.com> wrote:


On 07.11.2013, at 08:20, Max Leske <maxleske@gmail.com> wrote:

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

Date: Wed, 6 Nov 2013 19:23:47 -0200
From: Mariano Martinez Peck <marianopeck@gmail.com>
Subject: Re: [Vm-dev] Frequent SegFaults in PharoVM with Pharo 3.0
To: Squeak Virtual Machine Development Discussion
<vm-dev@lists.squeakfoundation.org>
Message-ID:
<CAA+-=mWDtHGQWSHx-m4u37Kj0UAMx=UG=qUCz+wMvgDT8BaQZQ@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

I just gave CogVM and NBCog a shot. Unfortunately I can�t use the images because they�ve been built with PharoVM and hang after load. At least on the Pharo CI there are no jobs that create Cog / NBCog images.

So no luck with different VMs.

Max



Thanks


On Wed, Nov 6, 2013 at 6:04 PM, Max Leske <maxleske@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