dbclean memory utilization

Ross West westr@connection.ca
Thu Feb 18 17:38:08 UTC 2010

(I've attached a .png file that shows what I'm talking about - the
system has 4gig, running freebsd 7.2/amd64, dedicated to dcc .116 with
default settings)

We've noticed that while cron-dccd runs the dbclean process nightly,
that it'll utilize a large amount of memory while rebuilding/cleaning
the dccd database. The dccd process uses (on our system) roughly 2.5g
of memory normally, and the dbclean process can take an additional 1
to 2gig at points.

Normally not an issue, but we've caught the system once or twice
(usually a week after a large influx of hashes that need to be
cleaned) touching swap, which in turn causes a huge change in system
dynamics - dbclean's execution time goes from like a minute to an
hour+ due to the swap churn.

Of course the real answer to this is "more physical memory" :) , but
I'm looking at other possible temporary fixes in the meantime. So a
couple of questions that cropped up:

- Would the removal of the swap memory cause dbclean any hardship?

- Would temporarily shutting down dccd while dbclean does it thing and
then restarting it cause any weird issues due to the db being
reloaded? (There's a second server that takes the clients' load at the
time, so I'm not worried about that)



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