My observation is that it does. At first I thought it doesn't. For
a month it was stuck constant at 11 MB. Then one day it began to
shrink, by a little every few days. In two or three weeks it has
dropped to 9.4 MB or so. During this time I actually added more
newsgroups and thus received more articles.
>but when EXPIRE reports so-and-so many bytes
>deleted, it only seems to mean that this space will be overwritten by
>new messages at the next IMPORT. NEWS.DAT doesn't *shrink* by that
>amount.
This also means that IMPORT will almost never encounter an
out-of-space condition, if you think about it.
>Meaning that when some spammer posts a five-megabyte binary, I can't
>reclaim that space on my hard disk afterwards without deleting my entire
>news base.
The disk space will be given back to you after approximately 2*t
days, where t is the typical expire time.
The way I see it, the newsbase adopts some pessimistic release
algorithm. When an article is deleted, the space is not released
back immediately; rather, Yarn will see for a few days if this space
is needed again. This makes sure that Yarn always gets the space for
IMPORT. When Yarn is quite sure that some space is not needed in the
long run, it will release it. Thus Yarn regulates (tries to keep
stable) the space it uses. We can further discuss this in light of
discrete control theory... :)
-- Albert Y.C. Lai trebla@io.org http://www.io.org/~trebla/