[Vm-dev] VM crash with message 'could not grow remembered set'

Phil B pbpublist at gmail.com
Tue Oct 10 19:58:00 UTC 2017


Clément,

Thanks for the info.  This is a Spur image.  Unfortunately it has some
sensitive information so I'll have to see if I can reproduce the issue in
one I can share.

On a related note, I seem to be running into more of these kinds of VM
issues as I'm attempting to scale up my image sizes (I can only imagine the
fun I'll be having with multi GB images) and am thinking it would be
helpful if the VM had the ability (even if it requires some sort of debug
build) to raise an exception in the image when a fixed resource exceeded X%
of it's maximum value.  Has a capability along those lines been considered?

Thanks,
Phil

On Oct 10, 2017 1:12 AM, "Clément Bera" <bera.clement at gmail.com> wrote:


Hi,

This is another limit than the out of memory error. Too many references
from old objects to young objects. The limit cannot be changed directly
from the image. However, if using Spur, you can try to change the young
space size, which also changes the remembered table size and might fix your
problem. To do so you can do:
Smalltalk vm parameterAt: 45 put: (Smalltalk vm parameterAt: 44) * 4. And
then *restart the image.*
Check here
<https://clementbera.wordpress.com/2017/03/12/tuning-the-pharo-garbage-collector/>
section
TUNING NEW SPACE SIZE for more info about that.

If you are using Spur, could you send us the image (if it is 500Mb could
you put it to download on dropbox or something like that ?) ? That way we
can reproduce and see what is possible. Normally in Spur if the remembered
table grows too big a tenure to shrink the remembered table happens, so
that error should not happen. Eliot is currently moving to another place,
so he might be busy. If he is available to answer, I guess he will have a
look, if he is not, I can have a look today or thursday. However I am not
interested in fixing pre-Spur VMs.

Regards,




On Mon, Oct 9, 2017 at 11:57 PM, Phil B <pbpublist at gmail.com> wrote:

>
> Is this effectively an out of memory error or am I hitting some other
> internal VM limit?  (I.e. can the limit be increased or is  it a hard
> limit?) I'm running into this when using the reference finder tool in a
> Cuis image.  (It's a moderately large image at ~500 meg)
>
>
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