Re: [Squeak-VMdev] Re: GC improvements

[John M M. <jo...@sm...>]

On Jan 19, 2005, at 2:38 PM, Andreas Raab wrote:

> John,
>
>> You miss the point that after N MB of memory growth, we do a full GC
>> event.
>>
>> The logic to do the full GC is either in the smalltalk code running as
>> active memory monitoring, or can be moved into the image.
>
> My criticism here is that the *default* without running that extra  
> code is not sensible. In other words, without active monitoring and  
> memory tuning you will indeed run out of memory. And that's just not  
> acceptable - there are plenty of people who will want to run a VM with  
> as little overhead as possible.

Well the VM change won't get triggered unless you supply a GC semaphore  
as part of doing active monitoring and memory tuning. No active  
monitoring and memory tuning then no new logic is run and we default to  
the historical behavior. My original point was that the growth part is  
in the VM, the GC trigger companion to the logic is in the image. The  
VM part will always run, the image part could choke. Thus a suggestion  
to move it into the VM.  However I'm leery about doing that since  
perhaps you don't want to say do a GC after N MB of growth, rather do  
it after a build a teapot, or after N http requests, having it in  
smalltalk makes it much easier to tinker with.

I will note that in VisualWorks the oldspace GC logic is a separate  
process (or two) and if they die your VW application will soon run out  
of  memory since  those Smalltalk processes control how oldspace  
incremental logic is run.   So leaving the logic in Smalltalk isn't an  
outrageous suggestion, but it's not fail safe.

What I could do is integrate your changes with mine over the weekend,  
and unless you want to take on that task?


> --
======================================================================== 
===
John M. McIntosh <jo...@sm...> 1-800-477-2659
Corporate Smalltalk Consulting Ltd.  http://www.smalltalkconsulting.com
======================================================================== 
===