Ok, if you don't have 

Smalltalk setGCBiasToGrowGCLimit:  "some magic number in megabytes"
Smalltalk setGCBiasToGrow: 1.

Then you can enter into a situation (unlikely) where the amount of free space is just less than enough to 
make the image grow, but enough to make the software do a full compaction. Think of it as a grey zone you 
approach if you can pass thru it promptly the image will grow, if your movement is just not correct then then 
you wander in the grey zone for days... The setGCBiasToGrow: alter that behavior so we pound thru the grey 
zone until we've allocated setGCBiasToGrowGCLimit: where we must do a full compaction (expensive).

However what's more likely is that you actually run out of memory, this is a I believe on windows 512MB? 
Other platforms may cap by default at 512MB or 1GB depending on the VM and it's default settings. 
For non-windows platforms you can use the instructions "found somewhere?" to alter the default setting. 

What happens in this case is when you approach the final bits of free memory via the hard upper cap the
VM will enter a endless cycle of doing GC work and finds just enough free memory measured in kilobytes to 
to make another GC cycle attempt.   If you are lucky this pattern will fail by the failure to allocated a needed 
method context and the VM will crash. 


I can only suppose that MessageTally  requires memory to run, is it statically bound? Or will it's memory 
needs grow forever? 


On 2010-10-22, at 10:30 AM, Alain_Rastoul wrote:

> Another precision, I have removed all gc tuning values I used before having 
> this problem, so the vm has all the default values for gc, I don't know if 
> it is gc or memory related.

--
===========================================================================
John M. McIntosh <johnmci at smalltalkconsulting.com>   Twitter:  squeaker68882
Corporate Smalltalk Consulting Ltd.  http://www.smalltalkconsulting.com
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