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Date:Mon Jan 14 11:52:02 1994 
Subject:Re: Clearing Memory Without Quitting Pop11 
From:jlc (Jonathan Cunningham) 
Volume-ID:940114.04 

> There should be a sys_restart() function that clears out everything
> since the system was started up. The nearest approximation is
> sysrestore. I.e. compile things you know you are going to need without
> recompilation, then create a saved image using syssave, e.g.
> 
> 	;;; save all VED files, then quit them then do	
> 	syssave('checkpoint.psv') =>
> 
> then to get back to the same point do
> 
> 	ved_w();		;;; NB write all files first.
> 	sysrestore('checkpoint.psv') =>
> 
> BUT if you are using X this may screw up any open X windows, etc. I
> don't know.
> 
> Aaron

It may be obvious, but ...
Using syssave for checkpointing is also useful when debugging a
program which runs for a long time before causing an error (ie at
least a few minutes) if the error is repeatable. (The "long time"
can either be cpu time or can be the result of a complicated
interaction with the user, if you can't easily run from a test-data
file.) The situation occurs when the error doesn't appear until
some time after it happens: sometimes you have to work backwards.

--jlc