On 30-Jul-06, at 9:09 AM, tim Rowledge wrote:

> I strongly urge you to not try saving an image in a background  
> process, except just possibly in a very high priority one. As Peter  
> mentions any other priority can be pre-empted and so all that  
> careful go-to-sleep code (take a look at the fairly scary list of  
> jobs to be done before the actual snapshot) could be completely  
> messed up. That could lead to both the active image and the saved  
> snapshot being unusable, which is unlikely to please you!
>
> Many years ago somebody at a large US automotive manufacturer put a  
> snapshot primitive call into a background process. The resulting  
> debugging work at PPS cost my team 5-6 man-months of effort and a  
> lot of aggravation. Bad idea.

Tim, I think the code suggestion from many months ago forks a  
background unix process that does the snapshot. It of course is an  
identical copy of the parent at the time of the fork maintained by  
the magic of virtual memory. The original parent process just keeps  
running and memory updates don't alter what the child process has.   
On a mulitple CPU that tosses the repsonsiblity of saving to another  
process at the cost of memory.


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