[Vm-dev] Problem with #garbageCollect and -memory parameter

[Mariano Martinez Peck]

On Tue, Nov 30, 2010 at 5:14 PM, David T. Lewis <lewis at mail.msen.com> wrote:

>
> Hi,
>
> I'm away and cannot check this right now, but if you look in the
> SqS/VMMaker archive there there are a number of recent updates that
> may address this problem. See the Montecello update comments for
> VMMaker-dtl.188, VMMaker-dtl.199, and VMMaker-dtl.200 for summaries.
> These updates would not be in any of the released VMs at this point,
> but I have a hunch that they will take care of this problem.
>

Hi Dave. Ok...after a couple of hours I could compile a new VM for MacOS
with VMMaker 205 and integrating all my changes :)
So....this was something I have to do since several months already hehhehe

Now, as you guessed, something  was related to that. Now, these are the
results:

normal:

Smalltalk garbageCollect   481957728
Smalltalk primBytesLeft 5738200

with -memory 1500m

Smalltalk garbageCollect    482093452
Smalltalk primBytesLeft 6444200


Now, at least it is not negative. But I wonder....shouldn't I have more
bytes left when I send 1500m ?
how can I be sure that the VM is actually tacking into account this
parameter?
can I check some parameter in Smalltalk vmParameterAt:
?

thanks!

mariano


> Dave
>
>
> On Tue, Nov 30, 2010 at 02:43:50PM +0100, Mariano Martinez Peck wrote:
> >
> > Hi folks. I am using the standard SqueakVM  4.2.5beta1U.
> > If I run normaly the VM with a normal Pharo image and I print Smalltalk
> > garbageCollect -> I get something like  492130460
> >
> > Now...if I run the vm with the parameter -memory 1500m  and I then print
> > Smalltalk garbageCollect -> I get a NEGATIVE number like:  -619402660
> >
> > I guess there is a problem in somewhere like ObjectMemory >> bytesLeft:
> > but I don't know...
> >
> > Anyway, the problem in my case is in SmalltalkImage:
> >
> > okayToProceedEvenIfSpaceIsLow
> >     "Return true if either there is enough memory to do so safely or if
> the
> > user gives permission after being given fair warning."
> >
> >     self garbageCollectMost > self lowSpaceThreshold ifTrue: [^ true].
> > "quick"
> >     self garbageCollect > self lowSpaceThreshold ifTrue: [^ true].  "work
> > harder"
> >
> >     ^ self confirm:
> > 'WARNING: There is not enough space to start the low space watcher.
> > If you proceed, you will not be warned again, and the system may
> > run out of memory and crash. If you do proceed, you can start the
> > low space notifier when more space becomes available simply by
> > opening and then closing a debugger (e.g., by hitting Cmd-period.)
> > Do you want to proceed?'
> >
> >
> > Since both of the first answers false because, of course
> garbageCollectMost
> > and garbageCollect are negative....
> > then I have that poup all the time.
> >
> > To fix this I have to posibilities:
> >
> > 1) Just patch this particular method to:
> >
> > self garbageCollectMost.
> > self primBytesLeft > self lowSpaceThreshold ifTrue: [^ true].  "quick"
> > self garbageCollect
> > self primBytesLeft > self lowSpaceThreshold ifTrue: [^ true].  "work
> harder"
> >
> > Notice that primBytesLeft is answering correct. Wait..I don't know if
> > correct, but at least possitive:  5691396
> > I think this is possitive because the primitive is not receiving a
> > parameter, and thus, Interpreter >> primitiveBytesLeft
> > evaluates the first part of the method, which just does self sizeOfFree:
> > freeBlock , and not the second part where it does self bytesLeft: aBool.
> >
> > 2) understand why it is negative and fix it from the VM side (I have no
> idea
> > how to do this).
> >
> > Now, in addition, I wonder if there may be other places broken because of
> > this....I am having some crashed and I don't know why :(
> >
> > Thanks in advance,
> >
> > Mariano
>
>
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